That whole thing should be either 4-lane divided or 5 lane undivided with the 5th lane being a center turn lane. Existing traffic levels are pretty heavy for a mere 2-lane highway. Plus US-377 is almost the only Red River crossing between I-35 and US-75. The SH-91 crossing over Denison Dam is almost a stone's throw from US-75.
The current plan has it as 4 lanes by 2028 until end of plan in 2045 with a request to AASHTO to realign the US 377 designation along the interstate, like US 77 elsewhere, and giving up roadway maintenance to to the cities. It's behind, on one hand because budget and on the other because Argyle won't annex the very tiny part of it that's not in a city already. I should say this is the part of US 377 between Denton and Roanoke. The part north of Denton isn't 4 lanes until 2037(? I think).
The way it goes is like this. City approves thousands of homes and strip malls for yummy property tax revenue, Aubrey's got like 4,000 houses going in. If you don't believe me just grab sentinel hub imagery. State is like, wtf Aubrey, are you going to pay us to widen this regionally important road that suddenly is over capacity? City is like lol no. Bye. State says, okay, 2037 then, BYE. (source: am regional transportation planner, formerly Collin County GIS/Planning)