Early voting has begun in Texas, and turnout is massive (always a good sign for Democrats), especially in the relatively-liberal urban enclaves. Yes, Texas does have relatively-liberal urban enclaves. Dallas, Houston, and San Antonio have gone for Democratic Presidential candidates in some recent elections, as has the region along the Mexican border which includes the large city of El Paso. Dallas has a substantial and open gay subculture, and Houston has elected an openly-lesbian mayor -- and then of course there's Austin. And recall that Texas has a large Latino population. It's far from a homogenously conservative state.
If Hillary does carry Texas as well as Arizona and Georgia, her electoral-vote total is likely to surpass 400 -- just the kind of massive rebuke the Republicans need to receive for inflicting Donald Trump on the nation as a serious candidate, and just the kind of sweep that will make a real mandate hard to deny. The odds are still against it happening. But not by much.