John Kasich is one of the mysteries of 2016. He's one of the candidates who, rather conspicuously, refused to endorse Donald Trump. Even Ted Cruz came around, and Cruz had real personal reasons to not do so. Not so with Kasich; he didn't even give an indication that he would vote for Trump. That, to me, is the minimum standard or party loyalty, to say you'll vote for a candidate, even if you won't campaign for them.
This is a surprise because at the beginning of the campaign, Kasich seemed to realize that Trump's supporters were a faction of their own in the party that were very much part of the Republican base, but who had been ignored. He was the Repubican Governor of the swing state that swung the furthest in Trump's direction; he could have positioned himself to take lots of credit for that. Now, it can be said that Trump won a big victory in Ohio in spite of it's Republican Governor, and not because of him..
Why did this happen? Why couldn't Kasich, in the end, say he'd vote for Trump and make a token appearance? He was, in many ways, closer to Trump on policy than, say, Ted Cruz. I can't believe he's got a future in the GOP at this point, and while he's pushing 70, I'm sure he doesn't like the idea of that. Why did he not come around? It's one of the bigger mysteries, as far as I'm concerned.
That's because you, for some reason, think that Trump's nomination has shed all Chamber of Commerce/Country Club/affluent/business-minded/whatever-you-didn't-like-about-the-GOP-type Republicans from positions of prominence or influence in the GOP any more than Romney's nomination had that effect on SoCons or this "Trump group" we all seem to think exists in any sort of ideologically coherent way (rather than a mass of frustrated voters that were frustrated for different reasons and have little in common).