To be honest, it isn't happening quickly but it is happening. I think it's the playerbase's fault though. They came in expecting this game to be a WoW killer and this amazing thing nobody had ever seen, then immediately started comparing everything in it to WoW. One big complaint is the end-game is dull. The game isn't even a year old, yet people playing somehow expect it to be even more massive than it is. So it's not 100% true or false, but somewhere in between.
Actually, scratch that. Their sales haven't dropped by much apparently. They announced a truckload of new stuff for their 1.3 update today at E3, including new playable species, a new planet to visit, new missions, new pvp, new instanced dungeons, and a new companion (HK-51, an HK droid like HK-47 from KOTOR )
It isn't official yet. They are most likely going to make it free to play to level 15 (which isn't much progress, that's right around unlocking your ship). I don't see it going full f2p, because it still has a huge following. They've got a lot of sexy new content planned for the entire year, so they certainly have the ability to win back people that left.