relocate 100 aircraft to Atlanta or Miami and start up ops with a vigorous schedule...Having PHL would lockup the NE.
I'm sorry, but your whole post is whacked. You are suggesting US deploy 29% of its mainline fleet into someone else's fortress? And one of -- if not the -- largest hub operations in the world while your at it?
FL is able to exist in ATL because DL lets them. US would be squashed like a roach with a swoosh.
To suggest CLT and ATL simultaneously is flawed. US has already had the problem of cannibalizing hubs because of proximity. At one time, it had hubs or connecting complexes in PHL/BWI/LGA/DCA/SYR/PIT/CLE/IND and DAY. They fought with one another and none of them worked.
MIA is a hub for AA. A uni-directional hub at the very corner of the country at that. East coast to points south with a little Europe, DFW and West Coast thrown in for fun. One cannot go from JAN to PHF via MIA on AA without trying very hard. US tried to have a focus city in FLL and it was a disaster.
And you suggest having PHL as if we don't already have it today. Last time I checked, US had a hub there already. In spite of WN, PHL's O&D makes it a good place to have a hub and -- news flash -- we've had one for years, in spite of its infrastructure challenges.