My two cents here for domestic hubs (don't know much about int'l hubs, so am going to withdraw my opinion on that):

*ATL: Gonna be here to stay. No way will DL close its' flagship hub. On a personal note, I like ATL. It's clean and pretty well-maintained. The employees, however, are hit and miss.
*SLC: Also staying. I can foresee a few small cuts here and there, but SLC will still remain the West's main hub.
*CVG: Gonna be dehubbed. Focus city. Kinda like PIT with US.
*JFK: International getaway. Less domestic connections.
*LGA: More of a domestic hub. Domestic connections, especially for the East Coast.
*DTW: Definitely gonna stay, but not as well-emphasized as ATL.
*MSP: A few cuts here and there, but will still be a hub for former NWA traffic.
*MEM: Anything's possible.

Wow, that's many domestic hubs. CO, AA, UA, and US only have three--DL/NW has 8 hubs combined (4 DL; 3NW; LGA being a new hub with the merged airlines).

I have a humble suggestion for a hub - Tulsa. While TUL may not be well known, I believe it would make a good hub because of the lack of weather problems (except for the very occassional tornado), it's smack dab in the center of America, and would offer more Texas-bound traffic. Anyone agree about TUL?