CCP's Reynir Hadarson believes that EVE Online could last fifty years or more. He indicates that developers will continue to build and that MMOs shouldn't be limited in the length of their appeal:
Asked if Eve Online could still achieve new things, he said "Absolutely, we will just keep building on top of it. MMOs do not have to age. The nature of a game like Eve is that there is no need for sequels - why shouldn't it run for fifty years?"
CCP recently released the 'Trinity' update for Eve, which offers an optional update to the graphics engine, as well as new content for the game.
Eurogamer has the rest of the article.