If the 2016 Presidential election taught Americans anything, it's that the states play a pivotal roll in choosing the President and recent polarization and realignment among the political parties has turned the vast majority of states into the "solidly Republican" or "solidly Democratic" camps. Or so we thought.
Recent demographic changes sweeping throughout the south and southwest parts of the country are giving demographers and political scientists plenty of things to talk about. In Texas, the Latino population is predicted to exceed the non-Hispanic white population by 2022 and Arizona isn't very far behind.
While it's true that a persons race isn't the only predicting factor for how they will vote, it is certainly a big one. States with large minority populations consistently vote for the Democratic Party while states with large non-Hispanic white populations consistently vote for the Republican Party. Therefore, it's not a big leap to conclude that major demographic changes like the ones were witnessing in the south will play a major role in realigning American politics for the next generation.
A lot (and I mean a LOT) will happen between now and the 2020 election that will determine the eventual winner of the 2020 election, but don't be surprised on election night if a state that has been reliably Republican for many years suddenly swings to the Democrats. The chances of it being Texas or Arizona are slim, but not impossible.
One thing I expect to see from this is each side catering to these changes in demographics. For example, the Democrats will double down on Hispanic support while the Republicans very likely will pivot their overall messaging to be more inclusive.
Of course perception could still take a long time to set in. So you're right, it is possible for a traditionally red state to turn blue in the short to medium term.
At least when it comes to the presidential election, as 48/50 states award electoral college points based on the popular vote in the state. For other elections that are done by districts, it will become a very contentious issue of where the lines are drawn.