Just saw the trailer, shoutouts to Leon coming back from the desert sands to join up. Now nearly all you guys no longer have to rely on Bayman and Bass to get a handle on our favorite girls (lol). From the looks of the amount of improvements and additions they showed (new poses, attack variants, possibly new ways to set up the Critical Blow attack and whatnot), It looks to be a straight up new disc (thought it's mentioned that it'll also come as a digital download) that may include everything from DOA5 on it from the start (perhaps with a previous game save on your console) at a discounted price (maybe $40, like BlazBlue Continuum Shift and Super Streeet Fighter IV/Ultimate Marvel vs Capcom). Just an educated guess, since they did that before with 2U and 3 back on the normal Xbox, and that seems to be the normal business quota for fighters this generation.
Personally, I enjoyed DOA5 a lot (even outside the ryona) so I'll definitely be picking this up Day 1. I also highly doubt the current TN wouldn't pump up the content to make it worth another disc since they seem to be pantering to their fans a lot with 5/5U. I'm just curious about who indeed would be coming back and who will be added to the roster that's straight up new. It may not seem like a large pool (though I bet we'll get someone else from Virtua Fighter as well) but I really think the roster's gonna make or break this being worth the effort for a lot of other people who already invested. Time to wait and see.
(P.S.: Thanks for answering, NNin. I was halfway thinking about trying out NG3: Razor's Edge just to see if I'd like it or not. Plus, Momiji seems right up my alley in what I like in a game gal. It's worth a shot I guess.)