The GOP Heading into a Dead-End?

Scenarios:
1. Trump wins the nomination and loses the November election.
2. Trump is denied the GOP nomination when support finally gathers around one of his opponents. However, that candidate is so weakened by the process that the Democrats win the November election.
3. Trump is denied the GOP nomination when support finally gathers around one of his opponents. Trump decides to do a third-party run and the Democrats win the November election.

In any of the 3 scenarios, it is possible that the GOP will lose the Senate as well. And if things really go downhill, the House will be flipped to the Democrats.

Awhile back, I made the following speculations.

Probably after New Hampshire and almost certainly after South Carolina, the Establishment will be faced with the following possibilities:
1. One of the establishment candidates has clearly broken through and it is a 3-candidate race with Trump/Cruz/Establishment going forward.
2. None of the Establishment candidates has broken through and the only alternative is to throw support to Cruz to stop Trump.
3. Cruz stumbles and Trump is marching and the Establishment candidates will need to lock themselves in a room and decide which one of their number will be the one to try to stop Trump.

Where we stand today:
Scenario 1 - Kasich remains in with Rubio from the establishment lane so it is almost a 3-candidate race but not quite.
Scenario 2 - Cruz's support seems to be slipping and so he may no longer be the receptacle of the anti-Trump vote
Scenario 3 - Cruz's problems of late can fall into this scenario but the Establishment hasn't lined up behind Rubio entirely and Kasich and Carson remain in the race.

Bottom line is that if the status quo remains in place, Trump gets the nomination.