Carlson used Monolith Productions' The Matrix Online as an example, explaining that the game's population had dipped down to fewer than 500 players by the time the decision was made to take it offline in 2009.
The breaking point where cost of maintenance just to keep the game up was ridiculous. Sometimes you just have to shut these games down.Determining when and how to sunset an MMO is never an easy task; Carlson noted that a studio should never "belittle the people who are deeply emotionally upset" about their favorite title shutting down.
The talk wasn't all about shutdowns, however; Carlson also discussed Sony's community management philosophy, which includes showing empathy to players, protecting developers from abuse, and using the player-driven community council to make more educated and agreeable decisions about the future of its games.
Gamasutra has a nice collection of quotes from the presentation, if you're into that sort of thing.