I would wait for Rubio's coronation as the Anti-Trump candidate until SuperTuesday. There are too many question marks about him and Kasich is still around.
I would agree. Kasich may be the stealth figure here. He didn't do well in SC but wasn't expected to--and the media attention is on Bush dropping out.
I don't think Kasich will become the anti-Trump, but he will continue to split that vote with Rubio. And this will allow Trump to squeak through with a 32-35% ceiling to pick up delegates in greater proportion to his vote totals.