Silly gooses! As 2016 approaches, the nation will probably start trending left again, most likely due to changes in demographics, the Democrats' ability to attract young voters, and the general swing every election (2014 was red, 2012 was blue, 2010 was red, 2008 was blue, etc.)
I doubt the GOP will ever have that much of a chance in Pennsylvania (minority population growth in the big cities & a lack of elastic voters help the Democrats)... Nevada and New Hampshire will also probably become safe for the Democrats soon as well. I also see VA and OH currently trending left, though this will take much longer and the Republicans still have a chance in these two states (as well as FL, obviously). Considering Colorado is a poor fit for Hillary and there are a lot of urban voters there, CO will probably remain a swing state for the time being.
Meanwhile, I can see Georgia and Arizona become swing states due to changes in demographics, and NC will probably retain its swing state status as time goes by. MO and NE-02 are also potentially competitive.
So here we go:
State Trends in 2012/2016/2020 -
Top Three Swing States - FL, OH, NC
State Trends in 2024/2028 -
Top Three Swing States - NC, GA, FL