I could see Jeff Flake flipping. He's not running again and doesn't seem to give AF about the GOP and dislikes Trump. I think if he flips it will be a combo platter of

1) The sexual assault accusation(s) (mostly Ford's)
2) The performance at his "job interview" making him seem too partisan and unstable for the supreme court
3) The long list of evidence that he was, at the least, a very sloppy drunk until at least 1990 or so. Even if you don't believe point #1, the dude has a long paper trail of things like throwing ice after a friend was arrested for a bar fight and making comments on a rental document (or something) about puking. I'm not too judgmental about these things, but an argument could be made that a supreme court nominee should have spent their 20s behaving much more boring than Kavanaugh, esp. when you factor in points #1 and #2.