The changes have many fliers wondering which carrier will be the next to “update” its loyalty program, with some eyeing the merger between American Airlines and US Airways as a possible catalyst for more such announcements. Airlines generally change their programs once every two to three years, said Tim Winship, publisher of FrequentFlier.com. “Whatever your miles are worth today, they are almost certainly going to be worth less in the future,” Winship said. Get the full story at NBC News.com