Even if Trump doesn't win on the first ballot, I can't see him losing on the 2nd or 3rd ballot. The GOP just cannot get away at this point in helicoptering in somebody else, and they aren't friendly to Cruz. If they cheat Trump out of the nomination, the Trumpistas will punish them by staying home, come election day.
The theory was always that the republican functionaries who are the delegates would switch their votes away from him as soon as they were legally allowed to do so. The question has always been 'to whom?'
Cruz has been active with the state conventions where the delegates are selected. That is how he was supposed to be able to get the 2nd or 3rd ballot victory. But liking Cruz now doesn't necessarily mean they'll like him in July. And with a butt whooping in Indiana, Cruz has problems even with his alternative method to gain the nomination. So the good news is Cruz may be out, but umm... that means... well... Donald 'If Clinton were a man, her penis would be half an inch long' Trump.
I think the Republican leadership just woke up happy for a moment then noticed they had a terrible headache, are in the hospital, handcuffed to the bed... and then they slightly recall getting into a car while drunk the previous night.
They don't know what to do. Option 1 is hell. Option 2 is hell. There is no Option 3. For a short while they had the underwear gnome thing going:
1) Stop Trump from getting nomination
2) ...
3) We keep the House, Senate, and the gain the White House
Now they realize they fucked up and it could destroy the party. They probably are trying to suss out polling to see how bad a Trump or Cruz Presidential run are for Congress. May have found out not good for either. Add to this the whole blocking a moderate nominee for the Supreme Court and there is tremendous poison in the electoral well, where people like Chuck Grassley and John McCain aren't looking good for re-election.
At this point, they keep pooping themselves and pressing the nurse button, but no one is coming to help.
Meanwhile the Democrats are laughing on the inside... and the outside, though in the back of their head, they keep wondering to themselves... 'The people aren't dumb enough to elect Trump... right?'