I mean, I think pollsters are having a very hard time trying to decide who will turnout in the race and if their turnout models are broken their numbers will be too, early voting starts in 11 days and I think TX is about 50/50 early voting so that will be our first indicator.
I would agree that is the main (only real) remaining source of uncertainty. If the early voting is good, we will certainly hear about it. The top sign of actual competitiveness will be if we see DSCC/Dem superpacs going in in any way.
TX Tribune always has great trackers with comparison bars to past elections