Donald Trump may have lost the majority of the educated white vote in Texas and Georgia, two of the states in which those populations brought about the shift from D to R in those states and were slower than other such people to swing significantly from R to D. But Trump may have done it. Obama having maxed out in much of the North and West, we may be seeing where the Romney-to-Clinton voters are this year in those national polls that have Clinton up anywhere from +9 to +12.. They aren't in California, Illinois, Maryland, Michigan, and New York.
Not convinced that Hillary will win the "educated White vote in Texas", but I agree with your fundamental point regarding this demographic having already shifted heavily Democratic in Presidential Elections in many solid blue states in the country.
There is room for the Democratic Party to expand within this demographic in places where the Republican Party managed to maintain an edge over the past 16 years five GEs, which is where we seem to be seeing the biggest swings based upon statewide polling thus far....
All being said, I still think that college educated Whites in Texas will still vote for Trump, albeit he might well only win with a plurality and not majority.
Hillary Clinton is not going to win the share of the 'educated white vote' that she can expect from similarly-educated black, Hispanic, or Asian vote. If she did, then she would be up 6 in Texas. But note well: under-educated blacks, Hispanics, and Asians have respect for educated successes whom they see as the most trustworthy leaders. If one uses formal education as a proxy for social class and economic success (such is usually so), then we have generally seen no great class divide in the politics of blacks, Hispanics, or Asians*. The class divide has gotten sharp among white people.
It is telling that although Texas voters under 65 split slightly for Hillary Clinton -- but voters over 65 (whiter, more rural, and with less formal education?) split heavily for Donald Trump. This might reflect conservative oldsters retiring to Texas (and Arizona) instead of Florida or staying put. But note also that younger, more educated white people are more cosmopolitan than their not-so-well-educated counterparts. If a clear-cut white, under-educated culture exists, then do well-educated white people fit into it? Probably not.
This may be personal experience, but I consider it illustrative. As a teenager I got moved from the very white rural Midwest to the San Francisco Bay Area, the latter a place of much ethnic diversity. My parents were afraid that I would have trouble adjusting to the ethnic diversity. I had trouble with the cultural divide between kids who took education seriously (whatever their ethnicity) and on the other side the low-life dopers and gang members. I got along well enough with black, Hispanic, and Asian kids who had much the same dreams as I did. I did not get along well with white punks who thought that I had more in common with them because of shared skin color and hair type.
Fast-forward a little over about forty years... and you find that my experience that I was much more like a middle-class black, Hispanic, or Asian-American than like the typical under-educated white person is what a typical young white adult with a college education has -- except that the well-educated white kid has seen far more ethnic diversity in the mass media. This applies as much in Texas as in California. The observation that Dallas is "Los Angeles without the beach" isn't especially new, as that applies to the car culture and the sorts of entertainment available in the 1980s. But like Houston, San Antonio, and Austin, Dallas is becoming more like Southern California. Such bodes ill for Republicans over the long run in Texas. As the suburbs get older those places that still have some rural characteristics (contrast suburbs of Chicago, Detroit, and Philadelphia) will have aging and often obsolete infrastructure in need of costly replacement and maintenance. As in California, real estate developers did just about everything on the cheap for maximal profits, and people are going to pay for that. Aging single-family housing will be demolished for crowded apartment complexes in which poorer people will have the inevitable enmity with landlords that tenants see as greedy rentiers making easy money.
It could be that this year, Donald Trump is simply an execrable candidate, and that with a more conventional nominee in 2020 the Republicans will do better in Texas than elsewhere, especially should Hillary Clinton become a failure as President. But this is not worthy of a bet for the Right. Donald Trump is so inept at maintaining a coalition that he is losing a big part of the educated white vote with his mind-assaulting demagoguery. Educated white people may be increasingly voting their culture instead of loyalty to bosses and landlords. That trend has been slower to take hold in some states (Arizona, Georgia, Indiana, and Texas) than in others (the Northeast and the West Coast); nothing says that it might not reverse.
*"Asians" is a reference to many different and disparate groups.
