Quite frankly, I don’t see it in 2020 or 2024. Though the state slightly becomes more Democratic due to demographic changes, Trump was a bad fit for the state. It may become a battleground state in the 2030s. But that’s a long time.
Trump (a bad fit for Texas) might run for a second term. If he does, let's see how he does there.
Texas will be trending Dem in the future for sure. I feel that swing was the beginning of a trend. Even if Trump was just a bad fit for Texas, now that he won his image is going to affect the entire GOP in the long run. Plus minorities, millennials, and well-educated whites are building up a strong coalition that will be swinging left.
I don't think 2020 will be the year Texas flips, barring a Democratic landslide: Georgia, NC, and Arizona will probably go there first.
They probably will flip before Texas.