The interesting question Syncaine asks is whether it would be theoretically possible that a MMORPG adds content and positive features at a speed high enough to keep players from ever reaching burnout. Syncaine is more hopeful there than I am. In fact, I don't find his examples very convincing. On his question "How long did you play EQ1?" my answer is "19 months", and that isn't terribly long, even if that makes it my second-longest time I spent in a game. And I think he is mistaken claiming EVE continues to grow. As far as I know EVE Online has started to decline in user numbers and activity since the Monocalypse debacle of Incarna earlier this year. I'd be grateful if somebody has a link to solid data about that.
I also believe that even a game with a continuously growing number of subscription isn't proof of player burnout not happening. As Blizzard themselves said, there are now far more ex-WoW players than current WoW players. A game can grow if more new players join than old players leave, and still have next to no original players left after a few years. The MMORPG you play forever might be an utopia for Syncaine, but I haven't seen any indication of that really happening over the last decade.