Apple told us they have 90% retention on iPhone, so I'm confident people will stay with Apple, because they have so far.
Based on their new margin disclosure for services, the services revenue is literally twice as profitable as hardware revenue, so they don't have to grow at the same rate to be more profitable over time. Think of that?
Also, hardware sales can spike up depending on features offered, promotions, and other consumer behavior. The rate of decline they saw this quarter is not likely to happen over time. Services revenue has been shown to be much more stable, which is why Apple is moving in this direction.
If Apple services are available on other platforms, that's great for the services narrative. They can provide their services to even more people and entice them to come to iOS for the "full" experience. They can bifurcate features, etc. I would be in favor of this because I believe in the services narrative. It's extremely powerful and will command a higher multiple for the earnings.
Microsoft has done this brilliantly, as an example. In fact, Microsoft is valued higher than Apple and just made $8B in profit to Apple's $20B. If Apple can get the Microsoft valuation over time, the stock will increase 3X.
Again (for the last time), customers retention rate in the future does not depend on historical data.
If a customer cannot justify the value of a product, then they are likely to walk away. Customers aren’t stupid (most of them anyway).