The GOP won't allow Trump to run under their banner again. That isn't to say he wouldn't win if he did, only that he is a threat to the powers that control the party. Those powers are remarkably similar to those who also control the DNC.

If Trump isn't allowed to run and a less ascorbic candidate is presented in his place the Democrats will take a beating like they have not seen before. Biden is doing nothing to give anyone any reason to vote for any Democrat and no Democrats are stepping up except those who aren't really Democrats (lookin at you Manchin) foolishly thinking they will capture some crossover Republicans.