Trump's ego is way to big. Cruz... Never. Trump is going to populate the White House with unknowns and no one that would be a conflict for him.

Yes, he has an ego and it's that ego that would propel him to make a deal with Cruz. See, if Cruz stays in the race, Trump will not get the nomination and everything after that is a moot point. Can't populate the WH if he is not in there. So, as much as he hates Cruz, he hates the idea of losing. Cruz knows he won't get the nom either. For them to team up is a Win-Win for them and a Lose-Lose for America.