But if Trump wins the nomination, I will vote for him.
My feeling exactly. However, i will add that Trump has a monstrous ego. I think he really wonders why he isn't polling at 100% - how could anyone think that anyone else is more qualified? When it gets closer to some kind of actual election, he may not be able to submit himself to a judgement by voters. His ego may not be able to accept that many folks will vote for someone else. In that case, he may feel forced to find a way to bow out.
And, if that happens, Cruz will be there to pick up the fumble and run with it.
If he comes off a knowledge and likeable, he's in it to the end.
As I have said elsewhere, there is only one candidate who can destroy Trump, and that is...Trump.