Its easy to write editorials, talk about anecdotes, and take a few polls. There's an awful lot of cheerleading on the right, thats for sure. But the Demographics are quite clear: Mitt Romney won the independents and the Republican turnout was great, but he lost the election because there were simply too many Democrats. Obama lost the over-45 vote in 2008 which would have been completely fatal in prior elections, but he wiped out McCain because the younger voters are actually voting, unlike the young slackers of Gen X a decade or 2 ago, and this new millennial generation is the largest in history, bigger than the Boomers.
Right now, the election outcome is a simple flowchart. 1) If the Dem base turns out, the Dems win, period. 2) If the Dem base does not turn out, and the GOP base does, the GOP probably wins, but they can't win if both turn out because their base is smaller than the Dems. 3) If neither side is turning out, then the independents start to matter a lot more. It wasn't always this way, back to Reagan's first term and before there were a ton of independents, people weren't very political and the electorate was very swingy. Now people have lined up and taken sides and there's not much swing anymore, its just a turnout game.
The GOP is losing demographically because GOP voters are getting old and dying, and the new generation is far more minority and progressive than in the past. Here's one article that does a pretty good job of talking about the Demographics: 2012 or Never
(you do have to wade through some liberal spin, ignore that part, only demographics matter)
Here's another fact that starkly spells out what is happening: if the Demographics in 1988 had looked the same as it did in 2008, forget about how the people voted in 2008, just take how the groups voted in 1988 and adjust the group sizes, then Dukakis would have won.
By the time we get to 2020, Texas may be a battleground state with that rapidly-growing Hispanic population. The bottom is eventually going to fall out over there, and then its over until the GOP inevitably lurches to the left to compete again.