If you're going to buy a Persona game and want Japanese audio, don't wait for the US release.
I'm 100% sure that Atlus USA won't keep the JP voices intact. That's been their modus operandi since time immemorial. They've already established themselves as the company who hates fun, after all.
I'm thinking of getting the JP version, but with so many backlogged games on other systems I own, that can wait a bit.