The only issue I've run into regarding old hardware support are with nVidia drivers (I have an old nVidia Goo 7700 GPU that isn't supported by driver versions past 304, which limits me to kernel 4.4 I believe), but that's not the Linux kernel's fault.
I'd rather the airspace be shut down for a few days than have a military laser accidentally hit a commercial jet. I'd prefer neither happen, of course.
If you care about audio quality, BT is the absolute worst option you can use to get music from your phone to your head unit. CarPlay, although still lossy, does a helluva lot less lossy compression than the A2DP/SBC BT profile that almost every BT-enabled head unit utilizes. I imagine this is true for AndroidAuto as well.