It was asked 10 years ago.
Since then:
Freehold is gone.
Pompano is gone.
Scarborough is gone.
Canadian track about to close.
It's happening but the spiral wasn't as fast as predicted. It will hit a cliff then be a step change smaller. Might stick around as a pure hobby.
As for what will people do. Many have already left the game in various ways. The lower levels will work menial jobs. Trainers will transition.
The biggest change will be people just retire and aren't replaced.
It's funny how this same question was being asked 10years ago.8