Why would Mitt get into the race? He has nothing to gain out of it, and it could only cost him energy and money. There's still a scenario in which he can be the nominee, should he want to be. That would be if Trump does not garner a simple majority of delegates. In that scenario, I'm pretty sure that the GOP can run whoever they please, lest there be permanent deadlock at the convention. If I understand the rules correctly, the delegates are bound on their first ballot to vote for the nominee to whom they're committed, but are unbound if no candidate receives a majority on ballot 1. Of course this is a formality, since everyone knows how many delegates are committed to whom. So if you're Romney and you want to be the nominee, all you have to do is call up Reince Preibus (of whatever the fuck his name is) and say, "Hey, Keep Donald under 1237 and I'm your guy." He doesn't have to listen to insults, attend debates, publicly fund raise--none of it--just show up and act as savior. Of course all this is simply to rehash what a dumpy candidate he was in 2012. He kinda made John Kerry look charismatic.