NW will not go tits up, all labor unions with the exception of the flight attendants have agreed to a contract.(with their hands tied behind their back).I cant comment on over seas maintenence, but in the US the maintenence is farmed out at smaller stations to the airport maintenence, for example in MSN, wisconsin aviation does maintenence work on not just NW planes but all the carriers that fly in. Unless the problem is too great then say, NW would send their own mechanics from one of the hubs down to work on the plane. These are NW mechanics. Mark my words, when NW comes out of bankruptcy in 2007, the ceos and all upper management will pay themselves huge million daollar bonuses. That is where the problem lies, they just asked their workers to take cuts to bail them out, then they'll give themselves a bonus for a job well done. In a nut shell most airlines NW, AA, Delta, continental, United are really not that much different. A lot of times it just comes down to the person whom is serving you, in otherwrds the customer service aspect.
Northwest did not reach an agreement with all their labor unions my friend, that is simply untrue.
The mechanics walked out on strike. NW filed for bankruptcy and imposed a wage scale on replacement workers and scabs that crossed the picket line...........trust me when I tell you that there was no agreement.
Also, the contract maintenance you are speaking of is done at smaller airports around the nation as larger airlines cannot staff them all with mechanics.
As far as all airlines being the same, I will continue to fly AA as they are the ONLY carrier still performing their own maintenance. Make sure you have the facts friend.