They might be happy that they can keep making V8s, but they have to know any future administration could easily outlaw any design that goes too far backwards. Such a car will also not be able to be sold anywhere else in the world. Heck, by the time they design, tool, and produce such a beast it could already be too late.
Well, just leave the catalytic converter out in the US variants of cars and pocket the difference. That's a far simpler change.
I don't want that, but given everything else that's going on, it wouldn't be a surprise.