A CarPlay-compatible dash unit is what, $500 installed at the most? Don't buy floor mats and undercoating at the dealer and whatever car you buy next can have CarPlay.
Assuming that it is possible to do so. I'd drop another Pioneer AVIC unit in the Leaf were it not for the fact that the OEM in-dash is the interface for a bunch of other stuff. A lot of newer cars have the same problem: the OEM unit you'd like to replace does more than play music.