Very cool stuff!
Greeneville which leaves more rurals to crack the Charlotte suburbs with and allows overpopulated NC-04 to become more based in Wake County.
I assume you mean Greensboro; Greenville is a small city out in the eastern part of the state.
Overall I think you're basically right on about NC. The big pain point is definitely the Triangle; even now the Republicans have to concede two vote sinks there and it's booming and moving leftward sufficiently to make that hard in 2030. A snake to Greensboro makes a lot of sense; they could also link the excess to the NE or Fayetteville too. Unlike Charlotte, you can't really crack the extra Democrats in that part of the world since there's relatively few ultra-republican areas in that section of the state.
They split Asheville in the 2010 cycle fwiw. That seat is annoyingly on the edge of being competitive, but is a bit more demographically and politically stagnant so the goons in the NCGA probably don't feel the need.
What would the hypothetical partisanship of a pure south of the canal district be?
Surprisingly not as Republican as I suspected; only 50-48 Trump, though with a massive swing from 2016. You'd still have to rate it lean R.