If not Christie who becomes the "Establishment Candidate" for the GOP?

[Mr. Morden]

How about a Walker/Thune/Rubio race?

I suppose Thune could run, but he's shown no interest so far.  If he really wanted to be president, he could have run in 2012, when there was a gaping hole in the field for a semi-competent anti-Romney.  That was also a year when Thune wasn't up for reelection in the Senate, whereas he is up for reelection in 2016.

[Mr. Morden]

I agree with bedstuy that there's no firm rule stating that there has to be a singular "establishment" candidate, and that it's perfectly possible for there to be multiple such candidates, a la 2008.  "Bridgeghazi" and other such Christie scandals might not be enough to bump Christie out of the race, but merely enough to weaken him, so that the establishment is more divided between him and other candidates.  The obvious choices for establishment rivals would be whichever Floridian runs and whichever Wisconsinite runs.

But who knows?  A lot of things could happen that are hard to anticipate now.  Bush could decide against running, while Rubio fails to get off the ground.  Walker could lose reelection, while Ryan decides to focus on the Ways & Means Committee chairmanship rather than run for prez.  If none of them gain traction, then you could have other folks, like Jindal, getting more of a look.