Those who have followed Blizzard Entertainment for a while will remember that the last project restarted more than once was the ill-fated Starcraft: Ghost, which doesn't bode well for the future of Titan. With World of Warcraft's subscription numbers in decline, it's possible that the company is moving in a different direction. No official statements have been issued regarding the development of Titan or any expected release window for the game.
[Update: ZAM reports that Blizzard has responded to that site's queries with the following statement: "We've always had a highly iterative development process, and the unannounced MMO is no exception. We've come to a point where we need to make some large design and technology changes to the game. We're using this opportunity to shift some of our resources to assist with other projects while the core team adapts our technology and tools to accommodate these new changes. Note that we haven't announced any dates for the MMO."]