How popular is this game really... How long will it stay?

So I love this game, however I have yet to reach level 80 with any of my character although I plan to get thee by the end of the year. But I was wondering how many copies has this game sold. I saw it said 2 million but the article was from like 2 months ago. Also since I'm not level 80 how crowded are level 80 zones. Lost Shores seemed like a failure because after the first chain of events, everyone seemed to abandoned it. I like how Guild Wars try's to add a new zone every month and it seems like the trend is going to continue. But the game seems pretty empty on lower level servers...

I plan on playing this game for another 2 years at least... But I know it's too soon to say, but what does it seem like at the moment.