I don't think AA feels the need to merge and the talk of their being a distant 3rd as a reason they must merge makes little sense.AA and US are two very different carriers.AA with 120 wide bodies,US with 26,AA with 124 757's,US with 23 and AA with 620 mainline a/c,US with 342.AA has global reach,good domestic coverage and the one world alliance with ba at heathrow,and jal in the far east.
US has been pulling rabbits out of its hat through 2 bk's, mortgaging most of its assets,and managing to convince investors better days are coming.If the demand for flying continues to improve,and fuel stays stable,they might hang on for a while.Soon they will have to deal with the aging piedmont fleet.Parts for the 100's which are not in production are getting hard to come by and some are reaching their cycle limits.
This might be a good thing as it will allow them to drop small airports that cannot fill a 50 seat rj.If the economy further sours,all bets are off as to the future of US.