The political right decided they hated Democrats more than they disliked Trump twice already. There's no reason to believe, if he wins the GOP primary, they won’t submit to his will once again.
The perception of Trump as a persona has changed quite a lot to the negative. Yes, he still has some loyal followers who will always support him but the sides have been cracking, even in his base.
In 2016 the field was too big and the perception of Trump as both wealthy and inevitable was wide spread, left right and center. That perception has changed except among his shrinking base.
It's inevitable that anyone who wants to win as POTUS is going to have some former Trump supporters who have switched to him/her instead. That's where the calculations should start.