There are reports from people with knowledge of CHQ "executive suite" discussions that US Airways is once again in M&A discussions (this should not come as a surprise). This time I'm not sure of the potential suitor, but it would not surprise me if US Airways' partner could be UA or AA.
Furthermore, I believe the reason the company is moving forward with new labor agreements is that senior management wants to be fully integrated before the next merger, which could be announced in the not-to-distant future.
Regards,
USA320Pilot