Lost in the hand-wringing over Apple’s iPhone 13% year-over-year slide in sales is the recognition that, in just 10 years, Apple’s iOS devices have generated more than $1 trillion dollars in revenue for Apple, according to Asymco founder Horace Dediu’s analysis. With $980 billion in iOS device revenues, and another $100 billion from services, Apple has built one of the most impressive businesses of all time.

Can it endure?

While it’s possible that Apple will cut into Android’s installed base, the real opportunity for Apple isn’t the hardware it obsesses over, but rather the software running thereon. Or, rather, the cloud that infuses that client-side software with data. This is Apple’s game to lose, given its propensity to tightly align hardware, software, and cloud.

Selling to the converted

By the end of 2018, Dediu estimates that Apple will have sold two billion iOS devices. While an impressive number, the downside is that it means the market is largely saturated. Among the smartphone class, users are more likely to dump Android for iOS than the reverse, and Apple is almost certainly going to encourage switching over the next few years.

SEE: Apple Pay’s best friend? Slow chip-and-dip EMV cards

But even if Apple wins few Android converts, it already has a bonanza in its massive installed base. As Dediu wrote:

An iPhone is unlocked 80 times a day. Assuming 600 million devices in use there are 48 billion sessions on iPhones every day. 17.5 trillion sessions every year. It is these instances of interaction and engagement which are desired by all businesses built on top of the ecosystem.

These instances of engagement must be multiplied by the quality of the customers which Apple captures. iOS users spend more and are more loyal than those on alternative platform thus qualifying the platform as “premium” and thus adding to its value in the eyes of developers, content producers and service providers.

As the install base of iOS increases and as users hire the devices to do more and spend more time with them the virtuous cycle of value creation will continue and accelerate.

Some of that continued growth will come from an unlikely source: Apps. Despite all the sky-is-falling-on-apps prognoses (like this one from Walt Mossberg), Apple reported on its earnings call the fifth-straight consecutive quarter of accelerating growth in App Store revenue, now at 43%.

Monkey gone to heaven, money gone to cloud

More of it, however, will come from cloud-based Apple Services, of which revenue growth jumped to 24% in the last quarter, landing at $6.3 billion, and has nearly doubled over the last four years. While still just 22% of iPhone sales (which dropped 13%), Apple’s Services revenue (comprising App Store, Apple Music, Apple Pay, and other such revenue) keeps getting bigger, and arguably will continue to do so even if iOS unit growth slows further.

Part of the reason is, as Apple mentioned on its earnings call, that “over time [Apple Services users] tend to spend more and more on our services.” The device, in other words, is the gateway to an ever-increasing appetite for Apple Services.

SEE Your app strategy is probably going to fail. Here’s how to fix it

Apple’s record with cloud services started off murky, with iCloud stumbling on sync issues and more. But over the past few years, Apple has proved it can not simply build services that run reliably at massive scale, but more importantly, it has built services that consumers are enthusiastic about using.

Apple Pay is one shining example. While it got off to a slow start, in September 2016 Apple Pay transactions rocketed 500%, with transactions in the month of September greater than all of fiscal year 2015 combined. Apple is still nowhere near saturation of use of the service among its customers, and has now expanded the service to the web.

Apple is also reportedly exploring offering original video content through the apparently inaptly named Apple Music. Such services only become more interesting as Apple introduces other form factors for engaging with them (e.g., Apple Watch), even if such new devices don’t match the iPhone for unit reach.

But to be clear: Apple’s future isn’t about the beautiful hardware it builds. It’s about the cloud, and the services that rain data down on those devices.