I don't have specifics, as I am not a nerd. 
However, I expect this to happen generally:
The current rural/"WWC" trends in favor of the GOP will continue until about 2024 or 2028 and hit a wall. Similarly, I think the Democratic trends in "wealthy/educated suburbs" will continue until about that time, too, but it will be because those places are actually becoming less wealthy, less educated and more diverse and lazy analysts will still just picture them as the places they used to be. "Democrats make huge gains in Lake County, IL!" will be viewed as Democrats converting wealthy, White Republicans rather than the actual cause of *most* of the shift, which is Lake County becoming much, much more diverse than it used to be; the latter fact won't stop anyone from thinking of it simply as *Lake County* with all of the classic connotations. Through all of this, the parties' actual policies won't really change from 2016; it will be a battle of perceptions.
After 2028, as more Boomers die off, the GOP will adopt a less culturally conservative (but not less socially conservative, necessarily) tone to court new and necessary voters, becoming pretty much what they were in the 1950s: a sensible alternative to overly idealistic Democratic rule (a party that now is much closer to Bernie Sanders than to Hillary Clinton). I think many states will be noticeably different, so it's pretty impossible to predict a map.
The whole comment about "Lake county isn't what it use to be any more" is the problem with the Republican now. It is also the reason why the Democrats will not become an idealistic party because America has long history of welfare chauvinism it will just end up like McGovern which in the end gave us Clinton. I think your giving the Democrats Party to much credit. By 2028 they would have shut down the Bernie wing if they have lost either 2020 or 2024.
I think many of Sanders ideas will live on to 2028 but free college will just be price controls on public universities tuition. Single payer will become a public option and $15 minimum wage will be comprised with Republicans to $8 maybe $10 in large cities. The farthest left wing legislation they'll have is voting rights.
