The GAO report that came out today by the government suggested that hub closures are very real. The US AIRWAYS time line of mergers trends this to be the case 100% of the time.
Empire: SYR gone
Piedmont: DAY, BWI gone
PSA, LAX, SAN gone
America West: LAS, PIT gone
Not sure if any other merger has exceptions, it does take time though.
Delta is closing MEM a couple years after the NW merger.
Maybe CLE goes in the United/Continental merger [showed its hand with last IAM TA that didn't protect CLE]
My guess is PHX is toast in a US AIRWAYS/AMR merger. Hopefully, it, PHL, and CLT hang around.
Southwest/AirTran: ATL is downsizing for AirTran
At any rate, MIA and DFW seem strong. Maybe ORD is strong as well for the AMR/US merger.