Lots of costumes would be nice. These next gen sequels should have at three times as many costumes as the PSone version. At the very least.
I wouldn't mind a training mode option that gives a measurement of the distance between your character and the training dummy. And a tool that showed tech frames and crush/sabaki frames. Character turns blue during low tech, green during mid crush, and yellow during high tech frames. Something like that would be useful.
Also...a multi-throw trainer with an option to see the CPU perform multi-throws at the fastest possible execution. I know there's some kind of just frame execution to the multi-throws.
I don't like going through story mode to unlock characters. Costumes sure. Characters not really.
I'd like to see Grace and Bahn make an appearance in future DOA games...or for Sega to make a sequel to Fighting Vipers. And Last Bronx while I'm making wishes.
Also when the option to record a match appears, the loser of the match shouldn't be able to do anything. In other games I've played against poor sports who don't mind recording a match when they win, but will avoid recording a match at all costs when they lose.
Story mode...eh. It's nice to have and what not, but I don't really expect much of a story from fighting games. Every once and I while I think "oh that's kind of interesting" but usually I don't give myself any expectations. They're all pretty much Enter the Dragon with a twist. As long as the endings are entertaining I usually don't care about story mode.
Speaking of story, I think it will be very noteworthy that this will be the first time Virtua Fighter characters have ever had endings. From the little footage of DOA5 we've seen, the VF crew has been given a lot more personality than they've ever had before, so it will be nice to see them not being so bland.
In terms of extras...they could throw in Star Force...or some other NES throwback.