Post Census Congressional District changes
Much has been made of the shrinking relative demographics of the GOP, as they grow older and more white while the country grows more diverse, BUT, if you look at the way the Census is likely to affect the apportionment of Congressional seats,there's a fair argument that the Democrats my be losing the geopolitical battle.
In the Congressional seat reapportionment, it's predicted that Congressional seats will largely be taken from fairly blue midwest and eastern states and portioned to the growing states in the South, sunbelt and west, and, as the Republicans currently control (or will likely control) the state governments in those growing states, they will control the redistricting, giving them more influence over what party gets elected in the newly drawn districts.
So, post 2010 reapportionment, there may be a burst of new Republican seats at the cost of safe Dem seats from the northeast.This will also effect Presidential politics as the growing Republican states will gain electoral votes as well.
However, I might argue that that this gain may be a high water mark in the longer term as a fair percent of the population increase that's driving those states to grow comes from more traditional Democratic voters, so, in the multi decade future, many of these growing states may slowly begin to turn tossup or Democrat as well, leaving the currently modeled GOP struggling for a geographic base.
However, in the next decade, the political geography seems to favor the red.
Just thinking out loud.