Also, it's interesting that the rural section on the east side of Greensboro from I-40 to US 29 is still just 65!!!
That's probably because it's a short freeway.
But it ties directly into I-85 south which is 70 mph.
I imagine it will all be increased to 70 mph once I-840 is complete to US-29 / I-785.
Now they need to increase I-85/I-40 between Greensboro and the I-40 split outside Durham to 70 mph. No reason they can increase the more urban portions of the I-73 and I-840 loop to 70 mph but keep the wide, straight 8 lane section east of the city at 65 mph.
Specifically, the independent 8 lane I-73 segment I had said before was probably one of the more urban, curvy sections I would
not recommend an official 70 mph limit for - yet they went ahead and did it before even batting an eye at the far more obvious ones. I imagine the 85th percentile speeds there are lower than some others they refuse to bump.
Also I-73 south and US-421 south should also reasonably go up to 70 mph. US-421 is still kept at a crawling 60 mph despite now being a full freeway for many miles south of the beltway.