Anecdotal, but I expect to keep my car until it dies. I have a 2004 3 series that's at ~240k miles. I would just factor the $80/year for 15 years into the price of the car when shopping.
And you really think that CarPlay will be supported over 15 years and you use a supported phone for all that time? Seems, in your car usage scenario you‘re better off with a subscription you can cancel any time.
I think that goes to the argument "It doesn't cost BMW money continously, it shouldn't you". It's actually quite likely that IF it is still used in 15 years, that's because the software was updated in that time to match new capabilities/usage patterns. This incurs real cost to BMW. But I suspect that BMW would recoup that cost by selling the updates.
