First, let me state I've not read a whole lot about carplay so I may be missing some critical info here. But here goes....
CarPlay making it into cars frightens me. Being someone who keeps cars for at least 10 years I worry enough about being able to fix/replace all the electronic gadgets already in cars. Now you toss in something like this, which requires an iphone, right? Now I'm locked into an iphone for as long as I keep the vehicle, in addition I could be locked into trying to keep a compatible iphone around for the life of the car. Who knows how long the lightning connector will be on new phones? And this comes from a reasonably happy iphone user.
I feel the unit should be a standalone unit, or at least have a solid set of base functionality to remain functional without a phone and for a very long time (maybe it does). I hope to have my next vette for about as long as my C4 has been around my family. Who knows where technology will be in another 30 years. I seriously doubt I'll have an iphone in 20+ year, or heck even in 10 years.
No conceptually on the other hand, better integration seems great, just needs to be far more standards based than proprietary so all smart phones will work well.