I really can't see Blizz making another MMORPG as it would cannibalize the WoW user base, and they would pretty much only gain money off the boxed game sales and not monthly fees as a starcraft or diablo MMORPG would not bring in many people who do not play WoW. I can see a console version as that would open up a new market, but I feel Blizzard needs to make either a regular rpg or rts to help Bnet from being turned into a ghost town, plus they get to keep WoW's user base. I think if they make a very different MMO game from WoW, such as a starcraft MMOFPS or MMORTS, or a PvP based and more mature themed Diablo MMORPG, which would not take as many users away from WoW as a similar MMORPG, thus preserving the WoW cash cow while gaining more monthly paying customers in the process, in addition to the money from the actual games sold. Those options make the most sense in money terms, which is how (I think) blizzard decides what games to do.