Today is your lucky day, as Capcom, in an odd twist of fate has actually confirmed content that is not DLC. It seems as if three new costumes will be coming to the console and PC version of Resident Evil Revelations, in the form of crazy sailor/pirate/ninja themed costumes for Chris, Jill, and Keith respectively.
Capcom is not revealing how you unlock these at the moment, simply stating that you should play through campaign mode, raid mode, and find "other unlocking mechanisms." If you're interested, Capcom will be streaming the content at 2PM EST on its Twitch channel today.
My guess is the 3DS version will be left in the wind. So much for early adoption and support, eh?
Resident Evil Revelations [Capcom Unity]