Democrat strategist Doug Sosnik has written a long, detailed analysis of the GOP's problems vis-a-vis the 2016 presidential election for Politico Magazine. To be sure, he is looking for problems, not for opportunities, but he finds plenty of problems to talk about.
In particular Sosnik believes what the GOP does to win seats in the 2014 midterm election will further alienate voters who only turn out in presidential elections. He takes as given that the GOP has permanently lost the votes of women, youth, and minorities.
Sosnik does not consider that the Dems could lose much of the white vote that they've gotten in the past, when the party's platform is increasingly captured by minority interests and agendas. That capture is likely.
Reading this article isn't fun, but he raises issues that need to be considered.