I think it will naturally happen in 8-12 years.
Well that was mainly because Romney was on the ballot, who was once a very moderate MA governor.
But I really don't see Massachusetts or much of the Northeast Corridor trending red anytime soon like some people think. Boston takes up way to much of MA, Wilmington takes up way to much of DE, Providence takes up way to much of RI, NY takes up way to much of, well, NY, and Baltimore+DC suburbs take up way to much MD for any of the rural areas of those states to have any effect. NJ and CT are more possible but NJ has lots of Philly and NY suburbs and CT might be held blue by the high levels of education in the Northeast. (I guess that applies to all of the Northeast though) Now of course that leaves PA. I think PA's Appalachian regions will make the state pretty red. Over time, I think other rust belt states will grow to be more red than PA due to Philly keeping the East blue.
Wow, this went wildly off topic and I wrote much more than I wanted too.
