Who does the GOP really have to run against Hillary?

Thus, here are the some possible Christie scenarios for 2016:

Christie manages to win the nomination and the GOP civil war officially begins.

Christie’s nomination launches a breakaway third party.

Christie’s nomination is the reason the base stays home.

Therefore, you can add “and Hillary wins” to the end of each sentence.

So if Christie runs and fails to get the nomination or decides against running at all who is left (I mean right) who can defeat Hillary?