I think Kasich is an opportunist that finally got the message thati it is time to quit before he just becomes a big joke for everybody.
Concur. I think Kasich really believed he would get the nomination on the 3rd ballot if he acted enough like a Democrat. He quit because it became obvious to him that would not happen. And, yes, this “realization” coincided with the exit of Cruz, because Cruz was the only one who had a shot at keeping Trump from a delegate majority.
Plus, Kasich probably figured that if he got out quickly, Trump might tap him for VP. If he does become VP, he will conspire behind the scenes to have Trump impeached. Count on it.