All vehicles.

Apple announced the total UI takeover option (though I’m not sure if it works today) but no car maker supports it on a shipping vehicle.

Many have announced interest but at this point we don’t know if it will ever be available, even if only on some kind of ultra-luxury car.

There’s always the aftermarket. If CarPlay stops being a standard option, that is the first thing I will do with a new car: replace the AV

As cars move away from traditional DIN stuff and more towards multiple screens with no physical “radio” on the dash in the classic sense… is that still an option?

It’s there’s a market, there will likely be a way. That’s one of capitalism’s strengths.

Maybe not for an EV.

The head units are so integrated and specific to vehicles now that I doubt that a third party unit would work and provide all that you need from it. The most you might get is a secondary screen that displayed CarPlay/AndroidAuto but then connected to the car via Bluetooth which is a serious downgrade.

I drive a 2021 Toyota RAV4. The CarPlay interface takes over the whole screen. It also does so in every rental or borrowed car I’ve ever driven.

Yes, in older designs with the smaller screens it does need to take over. EVs are moving to larger screens where there is room to place CarPlay into one section of the screen and keep other areas “native”.