The players that quit because there's "nothing to do at endgame" are the ones that only come back for an expansion and then quit again once they complete that stage. They move from game to game like locusts. There's nothing any MMO developer can do to keep them around because they'll always be able to complete the new content faster than anybody can program it.
There have been games over the last 12 years that have held my interest for a year or more at a time. Most of those I've revisited for extended periods as well. It is possible. It also had nothing to do with pay model.
The days of buggy and lag ridden 2 or 3 hour raids being acceptable have been over for a long time. TOR is proving that even as we type. I hope that they change more than just the billing style.