In the general election he will soften his position. He'll say that of course it's not possible to send them all back, but that they are going to set up clearing houses where Latinos will be required to begin the process of applying for legal citizenship, and that those who don't start that process will immediately lose all rights in this country so that they'll soon be begging to be deported.
People will say, "But that's totally different from what you said in the primaries!" And he will answer, "Of course it is. Next question. Sheesh!" Everyone will be stunned that he can simply shrug something like this off, but it will work. Just like it already has the first dozen times we thought he had killed his own candidacy.
He will soften his position just enough to get the percentage of Latinos he needs in order to win, paying extremely close attention to his numbers all the time. Those on the right will realize that if they don't turn out in large numbers, even though they feel betrayed on this issue, they will have four years of President Hillary. They won't be able to forget this because Trump will remind them about it over and over and over and over. And when it comes time to vote, they will turn out for him in droves.