Here is the most important bit from the American Airlines release:
While we've legally combined as one company, we'll continue to function as two separate airlines for quite some time, and very few changes will happen immediately. This is especially important throughout the busy holiday travel season, as our first priority will be delivering a smooth operation for customers of both airlines. There is no impact to any existing travel reservations you may have with American Airlines or US Airways at this time, and any mileage balance or elite status you have earned in either frequent flyer program are completely safe.
On March 31, 2014, US Airways will join the oneworld® alliance, adding more than 60 destinations to the oneworld map and expanding oneworld's global network to nearly 1,000 destinations in more than 150 countries, served by 14,250 daily departures.
Now for US Airways – here is the more interesting part:
We'll be exiting Star Alliance on March 30, 2014. You'll be able to earn and redeem miles on Star Alliance carriers until that date. Any existing reservations for travel on a codeshare flight with a Star Alliance partner after March 30, 2014 are safe, however, you'll be rebooked with a new flight number from the carrier operating the flight and you'll no longer earn miles or receive Star Alliance Gold or Silver benefits.
We will no longer offer codeshare flights for sale with United Airlines after December 9, 2013 and with Brussels Airlines, Lufthansa and SWISS after our exit from Star Alliance on March 30, 2014. Any existing reservations are safe, but you will not earn miles for flights on these carriers after March 30, 2014.
We plan to continue relationships with the following airlines, which means you'll be able to earn miles on these select partners even after we've exited Star Alliance: Aegean, Air China, Air New Zealand, Avianca, Ethiopian Airlines, Eva, Shenzhen Airlines, Singapore Airlines, South African Airways, TAM, TAP and Turkish Airways.
As our agreement with United Airlines comes to a close, US Airways Club members will no longer have access to United Clubs after March 30, 2014. United Club members will no longer have access to the US Airways Club after that date as well.
US Airways customers with Star Alliance Gold status will no longer have access to Star Alliance lounges after March 30, 2014.
Most of this was expected.
But flying US Airways is one of the best ways to earn 100% Aegean miles when traveling. It might be possible to continue to do this after 3/31/2014according to the statement above. That would be fantastic!