I'm off I-20 in Kaufman Co. They just recently lowered the limit to 60 on this stretch between Dallas and Terrell. It's a training zone for the HP....and they get lots and lots of training!
I disagree with you on your intimation that higher speed on a straight, flat, boring road will lead to more crashes.
I think that the higher speed will reduce the boredom and inattention that artificially low speed limits generate.
This is from a guy who grew up on the prairies. Higher speeds reduce ennui, and force you to pay attention. Even now, with the limit on the 2 lane highway from the family farm to the nearest major city set at 65, I seldom drop below 80. With my mother in the truck.
Drunk drivers are the obvious exception, obviously.
My guess is that the 80 m.p.h. speed limit will be applied to where the speed limit is now 75: mostly in Far West Texas on I-10 and I-20.