Was 2016 a realigning election

[pbrower2a]

No. It's too much like 2004. Take the 2004 map and give Michigan, Pennsylvania, Wisconsin, and Maine-02 but give Colorado and Virginia to the Democrat and you have the result. Michigan, Pennsylvania, and Wisconsin decided the election and by narrow margins.  Five states, three one way and two the other.

2020 will likely be the realigning election if Donald Trump or Mike Pence wins in a landslide, because such will show the permanence of Republican gains -- gains big enough to make the Republican Party the only game in town.  Either Donald Trump has solved all the problems that he said he would solve or his opposition has given up completely and decided that a fundamentalist-Christian and plutocratic America is all that is possible.

I see evidence that President Trump is extremely unpopular in Iowa, Michigan, Pennsylvania, and Florida, states that Obama won twice but Trump won in 2016, and North Carolina (which Obama won in 2008).

Realignments are not fluke elections. The 2016 Presidential election already  looks like a fluke. Americans do not like the results, as shown by Gallup and most other tracking polls.

Should the Democrat win back Florida, Iowa, Michigan, and Pennsylvania (probably Ohio and Wisconsin, as I have no polls for those two states, then we are back to the Obama maps as the norm unless we see a bunch of states returning to or joining the Democratic column. But I wouldn't bet against polls emerging that show Donald Trump is doing badly in those states.