A lot of the smaller "Mayberry" cities lost service, or at least mainline service, years ago - US' cool northern efficiency at work. I remember the day that Pitt-Greenville, Goldsboro, Greenville (NC), New Bern, Jacksonville (NC), Knoxville, Asheville, etc all had mainline service with 727/737s. I still wonder where the people we used to carry in/out of those places went. And that's not counting Virginia, Tennessee (except TYS), Kentucky, Georgia, etc. There are a lot of Mayberries within 500 miles of CLT.
Of those that still have RJ service, I suspect that some frequency will be exchanged for larger RJ's. The nice thing about the east is that a lot of those Mayberries are relatively close to each other so service could be consolidated in bigger markets within comfortable driving distance - ILM, MYR, CHS, SAV, etc. Again, much of this has already happened, except for still using a number of RJ's. It it results in enough traffic going to the west, by all means use mainline to take them to DFW/ORD. But if not, and for those not going west, you still need a collection point a lot closer.
My money is on CLT remaining a hub for the foreseeable future. Sure, there will be tinkering around the margin - S America flights may move to MIA, some of the Europe may move to PHL/JFK, fewer RJ's, more mainline, etc.
Jim