Both NA and UK have been confirmed by Sony (on the european playstation blog) to be receiving the demo of prologues before the game is to be released in march (specifically that europe will be getting it at the same time as the one in the US).
http://www.rpgsite.net/news/981/dissidia-012-duodecim-final-fantasy-prologue-confirmed-for-the-west.html
I think we can also take this to mean that the Legacy edition or something similar will be coming here as well (meaning two dlc costumes...I hope this is announced soon (if at all). I expect we will know more in a week or two. At least NA fans will not be left out if this is any indicator. In the off chance that legacy version is not released in NA I am sure the dlc content will be offered (SE likes money).
I am still hoping for a VI or IX character but considering everything SE has been saying and the limited space available for the games it looks likely that Gilgamesh and Prishe (the two secret characters) were the final characters to be announced. It would be nice if this was different but who knows.
Also to anyone who has been paying attention 3rd Birthday was pushed back for its release. I think this might be so they can include the costume for lightning dlc. That and they might be tweaking it a bit.
The final fantasy IV collection will have dlc and I would not be surprised at all if it were an assist rydia. Are there any other costumes the current characters could wear?
Also the introduction of assist characters and the lack of knowing of any aside from Aerith/Aeris I believe this to mean that there will be more in the game. SE probably wished to add more characters but did not have the space so did assists instead. Hopefully the next game can be released on the consoles and can have a system like soul calibur in which you get armor that actually changes. A Dissidia console version could be epic...not to mention could have easily 40 characters. Time will tell I guess. At the very least another game on the NGP would be nice...has better storage capability and what not no?