They're moving into a *very* crowded space.
Fantasy-based MMORPGs are very common. World of Warcraft certainly leads the pack, but you've got RIFT, TERA Online, Dungeons and Dragons Online, Everquest, Everquest II, Guild Wars, Guild Wars II, Lineage, Lineage II, and dozens of lesser-known "free to play/freemium/free in browser" worlds.
Even making it a more 'sandbox' sort of setting, it still is competing with tons of other MMORPGs in the same genre.