Well, for reference, here's the timeline of how they marketed SMT4, which was their last big game:
May 31 2012 - Famitsu ad teaser, official site opens with nothing but vague teaser images.
Aug 30 2012 - Soul Hackers released with a SMT4 trailer on the cart. Glimpses of characters and setting, no official details.
Sept 17 2012 - New trailer released online. Edited version of TGS trailer. Lots of gameplay footage.
Sept 20 2012 - Famitsu article blowout with details on staff, characters, demons, world setting, etc.
Oct 10 2012 - Full TGS trailer released online.
Feb 21 2013 - Famitsu announces the May 23 release date and the limited 3DS XL.
May 23 2013 - The game is released.
Going by that, I'll say that it'll be several months before we see anything, but they'll probably announce proper details for the game some time in early 2014.