I believe on there was some quote on TMC recently from someone at Tesla (or was it rumor?) that Tesla is looking to combining AP1/AP2 (or maybe just EAP?) codebase in a manner that can be maintained uniformly. This may already be happening to some extent, we know EAP emulates MobilEye in code anyway...
So it certainly seems possible Tesla is trying to combine various hardware iterations (AP2/2.5 too) within code to packages that can serve a multitude of different target systems - and thus allow bringing new features to even old systems to the extent of their capabilities. Then again, there is also some precedent that Tesla tends to abandon systems no longer in latest production cars (e.g. pre-AP parking sensors never got any improvements after AP1 came, even though technically they probably could have...).
Just now pre-AP Teslas didn't get the Chill mode... speculatedly because Tesla didn't bother to add Chill text to the aging Classic dial on pre-AP 7.x/8.x firmware...
P85 can't CHILL?