The two areas where radio PXP will survive and thrive - NFL and college sports. The reasons why are simple - the NFL has a national TV contract, while college teams (outside of Notre Dame and Texas) have their TV rights negotiated through their conferences. Radio is the *only* place where the team/school can control and make money off its media rights, sell/cater to local sponsors and have the "homer" announcer build a direct connection with the fanbase.
I know the Orlando Magic and Toronto Blue Jays have axed their radio broadcasts for TV. Several NHL teams have (Dallas, Buffalo, Carolina off the top of my head. Dallas and Buffalo have *always* simulcast. Carolina did so recently after new ownership bought the team, lowballed Chuck Kaiton and then eliminated the dedicated radio broadcast when he declined their offer).
Hockey is a bit easier to do because the fast pace almost demands a "radio call" even on TV (Doc Emrick made a career out of "radio calling" hockey on TV), but baseball and basketball are very different animals on TV and radio. If you try to radio call on TV you wear out your audience with too much description. If you try to TV call on radio, your audience has zero clue what's going on. Radio is about painting a picture. The problem with today's simulcasts is, the announcers TV call it. In the old days, it would be a primary radio call sent to TV.
But the reality of professional sports is similar to newspapers - both have ownership who will be looking to trim any "unnecessary" or "extra" expense. The radio broadcast is a pretty easy expense to cut as it doesn't generate a ton of revenue and a typical bean counter will say "why am I paying two broadcast crews to do the same game?" The next frontier before things being permanently cut will be that remote road broadcasts - especially for radio - will likely be permanent. The dropoff in quality is there, but it's fairly marginal. Meanwhile, the cost savings are enormous when you're looking at cutting out flights/hotel rooms for your talent for 41+ road games a year.