Write-In: Allowing Chris Christie onto the debate stage on February 6th
Without that, Marco Rubio places 2nd in NH, completes the 3-2-1 strategy in SC, and has a cakewalk to the nomination.
Maybe not the whole cakewalk thing. The fact is that Rubio was never going to win in some of those southern ST contests (and yes, Cruz would have stayed in the race.). So you basically get a more even three way contest. And this is assuming Rubio doesn't make some drastic mistake in one of the later debates. Remember - one slight change in history can really alter things in extremely weird ways.