Well, Trump has to broaden his approach to voters to build a broad enough coalition to win. All of the candidates do this in the general - they move to the center. The problem for Trump (and also Cruz a little bit) is that they have carved out very far right extreme positions that attract a certain voter. What will happen when they modify these views to appeal to the majority of more moderate voters. (immigration is the big one) We don’t know how the Trump base will respond, or if they will even acknowledge the shift. My guess is they stay on board, believe “their Trump” is the real Trump (the prolife one

), some will not even be aware the shift is taking place. I think a lot of these supporters just follow a limited set of media sites, very pro Trump.
I also question if Trump is capable of successfully changing, or becoming more presidential. This more self-controlled, in command persona exposes his shortcomings in experience, knowledge, diplomacy. Also his policy is being drafted as we go by advisors he is hiring; so expect rough spots, contradictions, misunderstandings as Trump articulates his positions…he is just spitting the stuff out that he is being given. I expect a fair amount of backsliding, slip ups - this alone could take him out of the running in the general pretty fast. (not sure he is really in the running in the general as we speak)