A friend with experience in government writes to offer this analysis of a second Obama term. He argues that we must consider a more complex set of possibilities than what I presented yesterday: whether the healthcare mandate has been upheld as constitutional (or not); whether the Senate remains Democratic (or not):
Two issues: mandate is constitutional/not, Obama releected with Democratic Senate/not. So four possibilities, let's take in order:
A re-elected Obama with the mandate found constitutional with a Democratic Senate might have some incentive to go moderate—their signature accomplishment is in stone—but will look for someting big. If that is fiscal compromise, they will go left, if only to make things difficult for Republicans in '14 and thus avoid the typical sixth-year losses.
A re-elected Obama with the mandate found unconstitutional with a Democratic Senate will go for broke. What does he have to lose? He's already said he will revise the healthcare law if the mandate is found unconstitutional, so that will very likely dominate the politics of 2013 -- and, with a Dem Senate, no particular incentive to compromise in the lame duck to avoid the fiscal cliff.
A re-elected Obama with the mandate found constitutional with a Republican Senate has little incentive to compromise. He won, healthcare will be implemented, and Republicans can only peck around the edges.
A re-elected Obama with the mandate found unconstitutional with a Republican Senate will be in no mood to compromise, even if he is weakened. It's a second term, not a first, so comparisons to Clinton 1995 are misplaced. He may sign some of what Congress sends him, but does this not seem like a recipe for gridlock and governing through regulation for four years?
So, using a basic 2x2 business school matrix, the most likely result is that Obama has little incentive to compromise. After all, the other factors you cite in your last paragraph, such as changing demographics and the media culture are secular trends not affected by the election.