When you promote a service model, well,  fans become disappointed if you stray away from that model. Splitting the community and support is the real issue here, not refusing to pay for additional content. It’s true for any multiplayer game, and it’s why sequels are such a problem in MMOs, where many sequels have struggled to surpass their predecessor. Generally you just divide and weaken when you think you’ll bring new blood.

Graphical updates, like Runescape or EVE Online did, or Ankama is preparing for Dofus, seem  much wiser to make a game look younger. Whatever is done, the persistent elements are crucial – database and communityhave more value to the players than improved graphics, new maps, or new features, and if you branch in a separate sequel, you’ll have to rebuild all that from scratch, no easy task even with the strength of the IP you’ve built.