If Trump or Cruz get the nomination, there will be a very large number of republicans who will be desperate to vote for someone besides Hillary. There are also always a good amount of independent voters who, like me, are probably dreading their choices right now.
The GOP base will fall in line behind Cruz - he'll do better than Romney in this regard - but he will have an independent problem. That doesn't mean he is unelectable. Hillary is a truly terrible candidate and the Dems are going to have serious turnout problems as these early primaries indicate.
If Trump is the nominee, I agree that some traditional GOP voters will stay home. Can't really say how many. But Trump is going to get a LOT of support from typical non-voters and crossover typical Dem voters - I think more than enough to make up the GOP support he loses. Again, the proof is in the primaries. Dem turnout is way down. GOP turnout is way up. At least part of that disparity is because folks who might ordinarily vote Dem are crossing over for Trump.
None of this is to say that Trump is my preferred candidate. But even with his sky high negatives, he would probably beat Hillary. People are underestimating just how angry a great many people are - not just conservatives - after eight years of Obama/Pelosi/Boehner/Reid/McConnell.
