I haven't asked this publicly before, though I've pondered this a lot... why can't US legally break the unions, especially the ones that don't want to play along with their wishes? I think this could be the idea the OP has, but hasn't directly come out and said it. Could US just spin those off into another subsidary and either create a new one or bring into it people from the old one that they want (i.e. selectively keep people)?
I'm by no means a business expert, but is there a legal way to dissolve unions? This will create some discussion, I'm sure.