Well,
If closing PIT would save money, not much the IAM can do about that... Not like you can have a strike over them moving the MNX work elsewhere in the system. Not everyone IAM represented from PIT could or would move either, thus new people in another location = lower costs. Pretty much the same thing they did with RES centers in places like SYR.
BTW That big nice white Bldg on the other side of the IND airport sure is quiet nowadays, so no one can claim such a thing is impossibile, nor can they claim that it is unlikely at this point.
Granted, if US goes into reorganization once again, US would still need mechanics, but in PIT...? Not to mention in reorganization or out, there is no real treat of a strike hurting US, unless you have been living under a rock, strikes at airliens are not allowed anymore by the government. Instead the two parties meet, and the union gets some of what they want, and the company gets some of what they want, like Heavy MNX offsite, and fleet service outsourcing...
Strikes sounds scary, but in reality, they are no longer allowed to effect the US transportation system (by the current administration, at LEAST until Jan)
Just reality, sorry...