I think to really appreciate how foolish it is to worry about literally regaining the loyalty of “Reagan Democrats” you need to look at the winning coalition Jimmy Carter assembled in 1976. That’s the coalition Reagan disrupted, and I think it’s safe to say that it’s a coalition that’s dead for good. It’ll be a cold day in hell before you see someone win New York and Texas while losing California and Illinois. At this point, the past is a different country in political terms.
UPDATE: And note that even in the more normal 1968, Humphrey carried Texas but badly lost in Vermont. Humphrey did better in West Virginia than in Pennsylvania which could never happen for a Democrat these days, and Nixon got a higher percentage of the vote in Oregon than in Oklahoma.