Id imagine there will be a influx of players for the new expansion but to me the game is back to its sh*tty exclusive self again. But honestly Id say give it a shot, you might like it you might not. If you don't then stop playing, if you do, keep playing. I myself take frequent long breaks and play for several months. If the Expansion is poor ill probably leave again, if it is fun ill likely play some more.
Presently I do not find the game itself to be overly enjoyable, mostly because my favorite job is a piece of sh*t that under performs in almost every imaginable scenario...The current endgame events are catered to time limits rather than the content, as such it requires optimal set up to complete with no way to progress using less than optimal groups, because the time limit says you lose if you don't finish in time.
There is lots of fun stuff, but it gets mundane pretty quick, At present I don't think the game would be worth returning to, but the fact that expo is around the corner is more than enough to give it a courtesy try, while FFXI to me has a lot of short comings at present, its always an adventure exploring new stuff.