I'm not saying nothing ever changes. The 1964/68 election cycles being an instance of huge party ID realignment, for instance (and the birth of the modern Republican Party). Party affiliations can change, which changes voting outcomes.
What I'm saying is that it's a bit too easy to get sucked into the liberal echo chamber where we all sit around and say "Man, Republicans are dumb. NOBODY I know would vote for a Republican, so there's no way they can win." It's a selection bias.
There are more than enough people who still think the Democrats are the scourge of all that is right and good in America. What'll be interesting is to see if the GOP (and especially the far-right wing, which is somewhat independent of the party itself) will be able to pivot their attacks from Obama to the Democratic Party itself. After all, Obama won't be on the ballot come 2016. If they spend all their efforts attacking him rather than the Dems as a whole, that's a major strategic blunder. My guess is that they'll keep primarily attacking Obama through the 2014 elections and then pivot hard to attacking the party rather than the man for the remaining two years.
Since the 2012 election, self-identification of Dems and Dem-aligned independents ("leaners") is down six points (from 50% to 44%)
Self-identified Republicans and Repub-aligned is virtually unchanged (42%, although there's a four-point drop in solid identification. But then there's a five-point drop in solid ID for Democrats.)
That's after ALL the clusterfucks of the last 13 months. The only major change is an 11-point growth in Independents who don't claim to align to either side. Now, I think some of that is a hipster effect -- it's cool to be indie these days. And some is an attempt by people to stay out of political arguments by saying "I'm an independent". But some of it is genuine discontent with the current political environment. The problem is, you can't bank on those people to all vote in ways that will benefit the Democrats.