I know he's a biased liberal and all, but this should be very troubling to the R's over the next decade.
As Nation and Parties Change, Republicans Are at an Electoral College Disadvantage
By NATE SILVER
Two more presidential elections, 2016 and 2020, will be contested under the current Electoral College configuration, which gave Barack Obama a second term on Tuesday. This year’s results suggest that this could put Republicans at a structural disadvantage.
Based on a preliminary analysis of the returns, Mitt Romney may have had to win the national popular vote by three percentage points on Tuesday to be assured of winning the Electoral College. The last Republican to accomplish that was George H.W. Bush, in 1988.
(more at the link)