Didn't the EC have a D bias for some time?
Things will change and GA, SC, and TX will get bluer with time. I think the Rust Belt will probably stay swingy but could get bluer as non-white populations grow assuming the GOP doesn't make huge gains w/ those groups.
That was basically just in 2012, because Obama just had to keep a few swing states. Indeed, all the Kerry states plus VA, NM and CO, which were already D-trending, was already enough to win reelection. This is why Romney always had a narrow path to 270, and on election night before CA came in, it looked like the NPV might be close to a tie. Of course, Obama won by 5 million in the end nearly 4 pts.
