Remember Persona 4: DAN already has a completed game engine as it's using the Project Diva engine. All they need to do are environment rendering/art direct, character models, animation and music remixes (if they aren't using existing material). It's essentially a reskin, a small team can do the project and the budget will be negligible.
I actually think this will be surprisingly successful for a lot of people. The Diva game doesn't interest me half as much as this does purely because I already know Persona 4's soundtrack and love it.