A player base is constantly eroding. If it doesnt have a shelf presence, new players won't even know it exists.
Nostalgic peeps coming back to UO is the only influx we have, and that isn't gonna be nearly enough to compensate the people leaving the game because:
1-the game is old
2-cheaters are never punished
3-EA obviously cares very little about this game
And those three are causing us to hemmorage players. I would wager that EA got a hell of a lot more money from duplicate accounts (for extra housing, shill guards for cheaters, etc) than they ever got from new players.
EA is letting the clock run down. At the moment, UO is obviously still profitable, or they would have closed it down. But I think right now its like an old arcade game in a video arcade... it makes enough return to cover its operation costs, and a bit more, and that bit more gets less and less. Once they cant get any more profit from it, they pull the plug.
Right now, as far as EA sees it (I am assuming), UO is that battered old Donkey Kong console... old, neglected, obsolete... but it still brings in enough silver to justify its existance. But eventually this exodus without influx will seal its doom and EA will tell us to hit the bricks.