I'm not a fan of Apple CarPlay, cannot comment on Android Auto, but I find the interface of Apple CarPlay horrid and how it interacts with the system (and this is beyond Cadillac). I think it could be the future but it has a ways to go before I think it's a valid replacement for the simplicity of in car navigation.

I think a path that hasn't been addressed is on the fly map updates and mapping provided by Google Maps or similar (i.e. Bing Maps) for in car navigation. Audi uses a version of this, but it eliminates the phone interface issue and provide a consistent up to date map with a true driver interface experience like current built in navigation systems.