We'll find out what happens over the next few months. For my part, I (literally) just signed up for the Barclaycards US Airways Mastercard 50,000 mile card offer. 40,000 points after first use? Sure, I'll spend $20 somewhere, collect the points, and wait for them to be shifted over to AA when the programmes are finally merged. And in the meantime, I've $12,000 of extra credit I didn't have before and that I won't be using, so my credit score will go up as well.
So far, what's not to like? You know, so far at least.