Seems unlikely for either to succeed, but that doesn't mean he wouldn't try, I suppose.

The problem is Tesla's stock price needs to remain sky high for it to work. That means keeping the market thinking there's a massive innovation coming soon, something huge that Tesla will have a monopoly over. Originally it was electric cars, Elon needed to convince investors they were so far ahead that competition wouldn't catch up. Then it was a fully automated factory, then humanoid robots. Now it's full self driving.

A move to ICE cars, a much more competitive market with lower margins, will be a signal that Tesla is a normal company that should be valued as such. ICE cars are also more complicated and absolutely need a dealer network for repairs. Those dealers have tremendous power over the manufacturers, too. Doesn't seem like something Elon would sign up for.