This is what we know from Activision Blizzard Q2 Earnings Call:
Titan will not be a subscription based MMO. Blizzard is still working on a new direction and plan for the project.
WoW is one of the last games that are P2P on today's market. Players will still have to pay subscription to play it because there's a lot of people interested in doing that. But in a few years I think the age of subscription based MMOs will be over. What's your opinion on this matter?