Quinnipiac's final poll of Texas in 2018 was 51/46 Cruz, so not sure why people are saying they underestimated Beto considering they got the race damn near exactly right and clearly well within the margin of error.
Trump has bumbled his way into making Texas a toss-up. Incredible that the GOP didn't pull the trigger on this guy when they had a golden opportunity to. Imagine where the party would be right now if President Pence handled covid-19 in a competent manner.
I dunno. If Trump had just randomly passed away or something, I agree that Pence would be in much better shape for November than Trump currently is now. But if the Republican party had thrown him under the bus, I think a huge number of Republicans would be extremely pissed off and demoralized and would just stay home. Look at what happened to Republican turnout in the 74 midterms after Watergate.