Well given the last trailer they released it looks like they have their HUD complete, and have the game running on an engine that works, all that's left for them I'd say is major cutscenes, fleshing out the storyline, designing and creating the zones, and level progression and skill systems, and then after that whatever else they feel like adding, so far they've shown us a city rendered fully in the game with interaction against a behemoth and an small open area what could take place outside of that city.
I'd say no more then 9 - 10 months of full dedicated work on the game, 1 month to debug the game and make sure everything is working, short term, I'd say a year from when they give us any information saying they're going full throttle on the game and not working on any major side projects to deviate from the games canon crew, i.e. Kingdom Hearts seems to be the only thing that could step in the way of that, and with 3D in the works, after that we can only hope they go back to fully working on the title like they said they would after XIII-2.