As for the GOP in 2016, I think people are underestimating the chance the Republican nominee in 2016 is the same as in 2012. The chance of it depends on the outcome of the 2012 race. If Obama's approval is a point or two north of 50%, it's probably too big a GOP loss for the Republican nominee to get nominated again. But if Obama's approval is between 48-50% and he ekes out a win with under 300 electoral votes, the 2012 Republican nominee may not be out of the running for the next cycle.
I actually think it's the opposite. If Obama's at 48-50%, a lot of Republicans will think it was a winnable race and blame the candidate for not being able to seal the deal.
If, however, Republicans make a respectable showing despite good approvals for Obama, then the 2012 candidate could claim they kept it close in a difficult climate and outperformed the fundamentals.
