Should a Democratic nominee for President win Texas in 2020, then that nominee is getting 400 or so electoral votes, more than any Democratic nominee for President since LBJ blew out Barry Goldwater.
"If x is going Republican, then said Republican is getting 400 electoral votes" needs to die as a narrative. It presumes that states do not shift their PVI over time, which they do. Trends exist afteral and thus any such concept flies in the face, almost presuming a static map that never changes except by the uniform swings.
That is not how it works, swings aren't uniform (see 2016) and trends cause states to shift relative to each other all the time.
There is a realistic scenario in which Trump wins the rust belt states again and loses Georgia with Texas only going Republican by ~5%.
Why? Differential demographics. All Trump has to do is replicate his margins with non-college whites and scare enough college whites to voting for him bc Dems be cray cray to hold the rust belt, meanwhile higher minority turnout and surge of college educated white millennial voters causes GA to flip and TX to be closer still.
I see Donald Trump as a political disaster nearly sure to go down in electoral flames if he gets the Republican nomination for President in 2020. That says more about Donald Trump than about any American political trend.
The big trends in Texas may be
(1) that Texas is becoming more similar to the rest of the US in its demographics, approaching the American average in educational attainment and urbanization. To be sure, it is possible for a state such as Utah to be strongly R despite having demographics (it is the most urban of states, as it has few people living outside the cities on the I-15 corridor (drifting onto US 89 toward Logan) and being highly-educated. Well, that is because of the LDS Church which is a cultural monolith in Utah. Texas has nothing like that.
(2) the Hispanic part of the electorate is growing fast, and even the middle class is not trending R.
OK, so if a state such as Michigan begins to have demographics analogous to those of the Mountain South (let us say Missouri) due to urban non-growth, then it can drift R.
This time -- should Texas go D, then the Democrats probably are getting 400 or so electoral votes. I have not seen adequate numbers of recent polls from Ohio or Georgia (I used to see lots of those) to refute or fortify your statement... if Bill Clinton could never win Texas despite being from a neighboring state and having affinities to Texas culture, then what Democrat can without getting fewer than 400 electoral votes?
Note well: Donald Trump is not the trend.
