Nothing wrong with that, it's historically accurate. The AA vote significantly raised for Obama, it's a fact. However a large part of that also has to do with blacks making up more of the nation than they did in 2000, for instance. So the total number of black votes will remain high enough, even if turnout drops. Same applies to young people, Hispanics, and other growing demographics.
The only shrinking demographic right now are white people, specifically older whites. Whites were 77% of the electorate in 2004; in 2012, they were 72%. By 2016 they'll likely be slightly below 70%. Likewise, voters over the age of 65 were nearly a quarter of the electorate in 2004. Last year they only made up 16%.
TLDR: The republican party, in its current form, is fucked. Barring economic collapse, scandal, terrorist attack, etc democrats should win the 2016 election based on demographics alone.