You must use iTunes to back up, via cable, right?
To be honest, I don't know if my significant other's phone (iPhone 11 Pro) can even connect to my car anymore through the cable. (Bluetooth being the only other option - which has significantly worse audio quality and issues like static or something of the sort)
Upgrading OS is the main source of frustration and time wasted in my pro-audio world. So I salute you - iOS10 survivor!
Note - listening to audio in cars, it's a compromise. It's never ideal, so I wouldn't sweat the quality - but you're right to question the reliability.
Use the good old, eco-friendly, headphone jack!
(All consumer wireless is ONLY instigated by Apple because it is cheaper for Apple, but consequently a poorer, less eco, experience for the world)
I’d rather they stick with lightning.
If you do, but want to switch to wireless carplay, there are adapters: https://cplay2air.com/products/cplaystreamer-wireless-adapte...
That said, I think Apple will offer both lightning and portless iPhones during the transition. They might make the "mini" phones be portless for example.