It really depends on the economic condition of those rust belt states 4 years from now. Whites without a college degree are very swing-able. It also depends on who the democratic nominee is. Sherrod Brown or Al Franken might be using a different strategy than Cory Booker or Kamala Harris will.
If the economies of the rust belt states start to improve and the Democrats secede the economic populism ground to Trump then the sunbelt strategy will probably come first. They'll emphasize social issues, double down on identity politics, and pursue a more hawkish tone on foreign policy. Their targets will be NC, AZ, FL, and maybe GA. College educated whites + minorities coalition.
If the rust belt is still crap and the nominee is Sherrod Brown or Al Franken then you'll see the rust belt strategy be in effect. They'll target whites without a college degree and emphasize economic populism combined with a more humble foreign policy. They'll likely moderate more on issues like gun control and possibly abortion. Whites without a college degree + minorities coalition.
JBE as the nominee might try to apply the rust belt strategy to southern states as well and build a minorities plus working class whites coalition to win states like GA, FL, NC, etc.
I agree with this. It's certainly the safest route to take. Trump, when he gets full hold of the economy, will probably bring the economy down which will likely cause frustration in the three Midwestern states of Michigan, Pennsylvania, and Wisconsin.
If Democrats are lucky, maybe even Ohio may swing back.