Of course, before LotRO there were already lots of high fantasy MMOs. Like, almost all of them, including Ultima Online, EverQuest, Final Fantasy XI, and World of Warcraft. Now there's Warhammer Online. If we're gonna be technical, Warhammer precedes all of these except for The Lord of the Rings and Ultima, but let's at least try to stay grounded here. Point is, developers and publishers keep doing high fantasy MMOs, and players keep buying them.
There are a few samples from other genres on the way -- Star Trek Online and The Agency, for example. But non-fantasy MMOs have had a difficult history. The only very succesful ones have been City of Heroes and EVE Online. Maybe Star Wars Galaxies or Anarchy Online, but that's being awfully generous. So really, ya'll; are you sick of this fantasy thing yet? Are you ready to give Sci-Fi another chance, or even something based on (prepare to gasp) the real world?