They're reliant on ecosystem lock-in. An iPhone begets AirPods, Mac, iPad, Watch and Services (Apple Music, TV+, etc.).

I use and like my macbooks, but the only reason I remain on iOS is for the integration. Auto switching with airpods, continuity camera, universal control, shared clipboard, etc.

The moment that third party software & hardware can use those APIs and integrate to the same level that Apple's own tech can, Apple no longer as a unique selling point (outside of maybe Advanced Data Protection) vs. any other smartphone.

I'd love to use my macbook, an Android phone, AirPods, and a Pixel watch all together to the level of seamlessness that Apple's own ecosystem integrates.