a 3-year cycle is long enough that I don't fear annualized "whoring" a la Activision
look at the GTA games: many shared elements, but each has its own setting, music, characters, world, and unique flavor
as long as we don't get Bioshock 2: Back 2 Raptcha, I'm all for funding and supporting the dev team to make "Shock-style" games (wrenches, guns, magic, and hacking).