I received the email as well. My guess (and only a guess) is for the vast minority of applicants who submitted to US Air but NOT AA, they will have to reapply. For those who applied to just AA or both and have a current aa.pilotcredentials.com account, there should be no action required. I thought there would at least be some container for me to check which acknowledges the new terms laid out in the email, but I couldn't find anything.