I'll be surprised if its' announced at Blizzcon at all. Blizz has never announced a new game at Blizzcon. Starcraft 2 and Diablo 3 were totally separate announcements. Only WoW expansions were ever announced at Blizzcon.
...unless of course they have switched ideas and DO now wish to expose this more towards the WoW-fans for hopes of converting them over - but even I doubt this would be true at this point.
But my theory still stands... if the subs aren't meeting their targets, they're going to start hyping/revealing Titan soon. The idea is to get Titan fully up and running and, most importantly, DEPENDABLY PROFITABLE for a forseeable long-term basis before WoW subscription loss income starts cutting into Blizz's other projects.