I think we may see another dark age at some point. But at least they phase in the improvements gradually rather than dropping a bomb on one specific year.
Really the difference will be in the volume sellers. The days of the 270hp Camry are almost certainly numbered.
Honestly though, I'm optimistic in the long term. People will always love performance, and where there is enough demand, manufacturers will find ways to supply it. There will be fun cars, though they may have to be lighter weight than the beloved beast to which this forum is dedicated.