The reign of the smartphone, the ubiquitous glass slab that has defined human-computer interaction for nearly two decades, is nearing its end, according to one of Silicon Valley’s most quietly successful venture capitalists. Jon Callaghan, co-founder of True Ventures, posits a provocative thesis: the current iteration of the smartphone will cease to be the primary interface for digital life within the next five years, and may vanish entirely from its dominant position within ten. For a firm that has consistently identified and funded market-defining behavioral shifts—with hits ranging from consumer powerhouses like Fitbit, Ring, and Peloton, to enterprise infrastructure giants such as HashiCorp and Duo Security—this is not mere future-gazing; it is a calculated investment strategy guiding a portfolio managing roughly $6 billion.
True Ventures has historically avoided the promotional fanfare common among modern VC firms. Operating largely under the radar from its Bay Area base, the firm manages 12 core seed funds and four "select" opportunity funds, using a disciplined approach to reinvest in accelerating portfolio companies. While contemporaries cultivate sprawling social media presences and podcast empires to court founders and secure deal flow, True has quietly prioritized cultivating a deep, recurring network. This strategy has yielded substantial results: Callaghan reports 63 exits with material gains and seven IPOs spanning the firm’s 20-year, 300-company history. Tellingly, three of True’s four successful exits in the fourth quarter of 2025 involved founders returning to the firm after previous successful collaborations—a testament to the strength of their network over public visibility. Yet, even amid the current frenzy of generative AI funding and monumental late-stage rounds, it is Callaghan’s unwavering focus on the breakdown of the established human-computer interface that merits the most attention.
“We’re not going to be using iPhones in 10 years,” Callaghan states emphatically, using Apple’s flagship device as a synecdoche for the entire paradigm. He quickly qualifies the timeline, adding, “I kind of don’t think we’ll be using them in five years—or let’s say something different that’s a little safer—we’re going to be using them in very different ways.”
The core argument driving this shift is elegantly simple: the smartphone, designed primarily as a visual, tactile, and highly distracting tool, is fundamentally inadequate as the primary conduit between humans and the burgeoning ambient intelligence layer. The friction inherent in the current interaction model—unlocking the device, navigating app sprawl, typing short messages, or drafting emails—is profoundly inefficient. These actions are prone to error, require visual attention that pulls us away from the real world, and chronically interrupt our cognitive flow, making the device a source of disruption rather than seamless intelligence augmentation.
The Rise of Ambient Computing and the Interface Crisis
The problem Callaghan identifies is symptomatic of a larger technological evolution. We are transitioning from the era of mobile computing to the era of ambient computing. Mobile computing centralized intelligence within a single, rectangular device; ambient computing seeks to diffuse intelligence across the environment, making it available contextually and instantaneously. The smartphone, requiring us to consciously pull it from our pockets and tap through menus to access intelligence, is inherently antithetical to the ambient paradigm.
This conviction has driven True Ventures’ investment focus for years, leading them to actively explore alternative interfaces across both software and dedicated hardware. This intuition is not new to the firm; it is the same foundational foresight that led them to invest in Fitbit before the wearables market materialized, to back Peloton despite hundreds of other venture capitalists dismissing the concept of connected fitness, and to support Ring founder Jamie Siminoff even after his public rejection on Shark Tank and numerous funding near-misses. In each case, the investment seemed premature or controversial, but the underlying bet was consistent: a fundamentally more natural or seamless way for humans to integrate technology into their lives.
The latest manifestation of this thesis is Sandbar, a startup developing a hardware device known as the Stream ring. Callaghan characterizes the device as a "thought companion," essentially a voice-activated ring worn on the index finger. Its mandate is narrow and deep: to capture and organize spontaneous thoughts via voice notes. Unlike multi-purpose devices like the Humane AI Pin, which attempts to replace the phone, or health-focused wearables like the Oura ring, Sandbar is defined by its singularity of purpose. "It does one thing really well," Callaghan explains. "But that one thing is a fundamental human behavioral need that is missing from technology today."
The device is designed not for passive, all-day audio recording, but to be an immediate, low-friction digital partner when inspiration or a critical task strikes. Leveraging sophisticated AI to process and structure the captured thoughts, it represents a radical departure from the app-centric philosophy of the smartphone.
Behavioral Investing: The Peloton Principle
True Ventures’ alignment with Sandbar’s founders, Mina Fahmi and Kirak Hong (who previously worked on advanced neural interfaces at CTRL-Labs, acquired by Meta), was driven less by the gadget itself and more by a shared vision. True had spent years mapping out the future of alternative interfaces, meeting dozens of teams. Fahmi and Hong’s approach, rooted in minimizing cognitive overhead, resonated deeply.
This investment philosophy echoes Callaghan’s famous rationale for backing Peloton: “It’s not about the bike.” While the hardware itself was compelling, the true value proposition lay in the new behavior it enabled—a sense of community, immediate access to high-quality instruction, and integrated data tracking that fundamentally altered the home fitness experience. The bike was merely the vessel. Similarly, Sandbar’s Stream ring is not just a gadget; it is a catalyst for a new behavior—immediate, frictionless thought capture and retrieval—that True predicts will soon become indispensable.
This focus on behavioral enablement over technological novelty allows True Ventures to maintain its disciplined capital strategy, even as the broader market floods with capital seeking exposure to AI. While generative AI startups routinely secure nine-figure seed rounds at billion-dollar valuations, True maintains its core competence: writing seed checks typically ranging from $3 million to $6 million for 15% to 20% ownership in companies that often find their way to True first. Callaghan stresses that while the firm is prepared to raise additional capital to scale successful ventures, there is no appetite for raising multi-billion dollar funds purely for the sake of size. “Why? You don’t need that to build something amazing today,” he asserts.
The Cautionary Note on Infrastructure CapEx
Callaghan’s measured approach extends to his analysis of the current AI boom’s structural economics. While acknowledging the transformative power of the compute wave—and even suggesting that OpenAI could realistically achieve a trillion-dollar valuation—he expresses significant concern over the staggering capital expenditure (CapEx) commitments underpinning the infrastructure layer. Hyperscalers are projected to spend upwards of $5 trillion on data centers, advanced chips, and energy infrastructure.
“We’re in a very capital intense part of the cycle, and that is worrisome,” Callaghan notes. He points to the dangers of circular financing models where vast sums are raised based on projected infrastructure demand, potentially creating a structural fragility if the application layer—the layer where consumers and businesses actually derive value—fails to monetize effectively or quickly enough to justify the foundational investment. This mirrors historical technology cycles where infrastructure outpaced practical utility.
However, his skepticism regarding the infrastructure cost is paired with profound optimism about the resultant opportunities. Callaghan firmly believes the greatest value creation lies ahead, specifically in the application layer, where these new, non-smartphone interfaces will unlock entirely new forms of consumer and enterprise behavior. The bottleneck is no longer processing power or data availability, but the archaic mechanism we use to interact with that intelligence.
Industry Implications: The Battle for the Next Default Interface
The shift away from the smartphone is not a slow decline but a fundamental disruption of the platform wars. For over a decade, the interaction model was dictated by Apple’s iOS and Google’s Android. The next decade will be defined by the "Interface Wars," where the winners will be those who master ambient interaction—voice, glance, subtle gesture, and eventually, neural interfaces.
This trend is already evident in market data. The global smartphone market is saturated, registering sluggish annual growth barely exceeding 2%. In stark contrast, the wearables market—encompassing smartwatches, rings, sophisticated hearables, and emerging voice-enabled devices—is consistently expanding at double-digit rates. Consumers are actively seeking specialized, context-aware, and less visually demanding ways to interact with information.
The challenge for incumbent tech giants (Apple, Google, Meta) is immense. They must either fundamentally reinvent their dominant smartphone platforms or successfully transition their user base to novel forms of dedicated hardware, a task fraught with risk, as demonstrated by the mixed reception to early attempts like augmented reality glasses and AI Pins.
True Ventures is betting on the specialized, single-purpose device—the Sandbar ring, for instance—as the initial bridge to the post-smartphone world. These devices sidestep the complex general-purpose utility of the phone, focusing instead on optimizing a single, high-value human behavior. This approach is intrinsically less risky than attempting to build the "next platform" from scratch, allowing a smaller, disciplined VC firm to secure significant ownership in companies poised for acquisition by the giants desperate to acquire the winning interface model.
The Investment Philosophy of the Fringe
Ultimately, True Ventures’ strategy circles back to Callaghan’s core investment philosophy—a romanticized yet deeply practical understanding of what true early-stage innovation requires. “It should be scary and lonely and you should be called crazy,” he says of the process of investing in truly groundbreaking startups. “And it should be really blurry and ambiguous, but you should be with a team that you really believe in.”
Investing in the future interface, whether it’s a connected stationary bike, a video doorbell rejected by mainstream investors, or a voice-activated ring for capturing thoughts, requires an ability to see beyond the immediate product and understand the behavioral void it fills. Five to ten years later, as the Fitbit, Ring, and Peloton stories attest, the blurry, ambiguous vision either crystallizes into a market-defining reality or dissolves.
Given True Ventures’ consistent success in identifying hardware that enables these new behaviors, the financial community and technology developers alike would be wise to heed Callaghan’s prediction. The shift in human-computer interaction is not theoretical; it is already underway, and the end of the smartphone’s unchallenged dominance signals a massive opportunity for the application layer innovators poised to define the next default interface.