People dont know it exists people wont play.
Thats the majority. The players that have left either got suckered in by the shiny lights of wow (makes me want to vomit) or left because of the imaturity of other players. and immature players trying to be top dogs. And also for the lack of help in game.
Speak for yourself. I left because EA systematically removed every dynamic challenge out of the game. As they did, they also completely gutted the atmosphere of the game by adding an excess of numbers, statistics and other modifiers to weapons and armour, effectively converting the game from being primarily player-based to being item-based, which is exactly why I played UO over, say, Diablo 2.
UO now offers little over other games that it competes with, in my opinion. It also shows as it bleeds players daily to the competition. There's little left in UO that cannot adequately be found elsewhere.
Furthermore, you can no longer sell UO. There is no way to sell a game that looks as dated as it does. Even if they did bring back the gameplay of UO's prime, gameplay odes not sell. Graphics do. You cannot play a game from the box in the store - you can only look at the pictures on its box. Graphics sell a game, and gameplay keeps the players around. UO is beyond being able to be sold via advertisement, and will only survive due to word of mouth. Currently, word of mouth does not bring the players in, and so UO is dwindling to eventually evaporate away.
It will be an extremely sad day when it does, because UO, by far and away, holds some of my best gaming memories without a doubt. Nevertheless, it has been a long time since UO was at its prime, and thus there is little left to keep players around besides nostalgia. Eventually, though, that evaporates, and you see the gradual loss of people.
UO will not close its servers, no. However, you will see a gradual decrease in players until the world is so sparsely populated that it becomes little more than a single-player game. EA will never reduce the landmass of servers to try to bring the population together because that means removing content, not to mention a large swag of other issues such as housing, so the population density will decrease and eventually result in it dropping below a critical amount, at which the game will become no more worth playing than a singleplayer emulated server.
edit:
I should elaborate: I see mythic as one of the best, if not the best, dev team in the industry. If
anyone can save UO, it is them, and I have immense respect for them after watching DAoC's life on and off and participating in WAR's beta and release. UO is in the best hands it has ever been, but even this cannot save it from the condition it has been left in. Not even they are amazing enough to manage to pull UO out of the downward spiral it is on. I know I certainly couldn't without immensely pissing off the current player base, which is something they would not do and therefore something that I think is largely impossible to achieve.
If they do it, though, I will certainly eat my hat.
PS: