I think Cruz *may* catch fire in two scenarios (or a combo of the two).
1) The establishment really gets worried Trump will win. Since he doesn’t need money they will see the writing on the wall that RINOs are not wanted this year and then back Cruz so that Trump doesn’t win. Cruz picks up establishment/RINO support giving him enough to pass Trump.
2) Trump finally says something that really does upset people and they have to move to another candidate. Cruz takes a lion share of Trump supporters, but with Trump winning in the leaning Republicans and not the die hard Conservatives—this isn’t a solid way to victory for Cruz.
I really like Ted Cruz but his supporters just can’t accept the fact that he has an almost impossible path to the nomination because he is just too conservative for the average republican voter. I’m conservative but I understand that most republicans are middle of the road or slightly right of center. That’s part of Trump’s appeal. He’s not the most conservative candidate but he’s conservative enough. He also has a better chance to win the general election.