If I remember correctly neither will ever be In a Tesla because Tesla would have to give them far more access to their system than they want too.
Naw if I remember correctly it was actually access to screen real estate in that CarPlay in particular required taking over pretty much the entire screen which obviously wouldn't work with the model 3 but that requirement has since relaxed so could be possible now and unfortunately I can't find it so take it with a grain of salt but I recall seeing him respond with a "maybe" or "working on it" to someones tweet asking for CarPlay in the last year