Are the Midwest and the Northeast slowly slipping away from the Democrats?

[Southern Senator North Carolina Yankee]

The problem for the sunbelt is that is that everything has to be considered relative to the following factors:

1. Southern whites vote Republican at inflated rates in the South because of racially polarized politics
2. This racial polarization is heavily skewed towards Baby Boomers and older voters.
3. Younger voters are going to be progressively less Republican as white voters revert to the mean with generational change.
4. Assuming Democratic support among African American's in the South remains constant (I think it will because that is where Republicans are in power and are cutting their access to voting), this portends an ever deteriorating situation for the Republicans in states like MS, GA and TX.

Therefore, even if Republicans avoided the bleeding among college educated whites, the simple "normalization" or "de-southernization" of College educated whites down to averages in the other regions of the country, portends the reduction in the overal white vote substantial relative to a constant Democratic performance among a solid 35% and growing African American block.

Lets say in MS that African Americans make up 38% of the Electorate and whites are going 80% Republican. 
                D            R
38*.9 = 34.2%     3.8%

62*.2 = 12.4%  49.2%
total:     46.6%    53%

Lets drop it down to 65% Republican, which is still one of the highest White GOP %'s in the country.
                D             R
38*.9 = 34.2%     3.8%

62*.35 = 21.7%  40.3%
total:      55.9%    44.1%

MS votes age 65 and older are R+40. MS voters 18-29 are D+3 and that is based on 2014 Exit Polling. A similar pattern occurred in 2012.

Trump goosed the White vote in 2016, which basically delays the inevitable. You cannot goose up a corpse to go vote.