Whatever it is, MMOFPS/RPG/RTS, I bet that they will try to tap the console market with this one. They already got one extremely successful PC-exclusive MMORPG so from a business point, it would seem to make sense if they would try to take the lead in the console MMO space now. That makes an MMORTS unlikely so I'd expect a MMORPG or MMOFPS or maybe a hybrid (further "dumbed down" gameplay compared to WoW so it'll work with a controller only). Probably with voice chat as the only way to communicate with other players so PC users do not get an advantage from having a keyboard for communication. That is, if there will be a PC version at all...
We'll find out when they make it official I guess.
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*** Born to troll ***