Looked into this, because I've been thinking of moving to Miami lately, and spent a lot of time there during remote working. Apparently Miami has donors for a new stadium, but nowhere to put it. Mayor of Coral Gables even called it "a stupid idea."
I don't think Miami is getting an on-campus venue, no matter what... but I will say people in South Florida still root for the U. They haven't lost fans and you even see a lot of U shirts/hats/etc on South Beach, out at events on the mainland, in traffic, etc.
https://www.local10.com/news/local/...o-build-new-football-stadium-in-coral-gables/