I think it would just force Republicans to go all in on the industrial/post-industrial Midwest and retirees (hold Florida, NC, maybe not get wiped out in AZ), on the assumption that the South is giving out. There would end up being little or no difference in family income between the party coalitions. Democrats are gradually able to contest the Plains and Republicans the Northeast (except for MA as Boston seems to be following the Southern/Western metro trajectory). Small cities become the most important electoral battleground.
They haven't repeated per se in every single election like 2012 but 2016 trends are just a further culmination of 88 to 2016 trends. The two best counties to show this are Anne Arrundel Md and Jefferson TX. Sure they actually flipped in 2016 but the margins or atleast PVI generally kept growing narrower and narrower. I wouldn't say they are certain to continue but in the medium-longish term that is exactly what has happened.This is a general idea of course. Like rural New England is a bit different.
