I expect Persona 5 to be on PS3.
That is all I feel even moderately sure of, but there are no announcements and it isn't like Atlas hasn't made games for a series previously exclusive to one platform exclusive to another (see: Nocturne). I feel pretty sure we'll see a 360 version, considering every HD game Atlus has been involved with has been PS3/360.
Atlus, unlike most of GAF, doesn't have anything against Nintendo. They have a fanbase on Nintendo hardware and, it seems to me, must have a pretty good relationship with N right now to be given the greenlight to develop SMTxFE. If the game multiplats to a third system, my guess would be Wii U.
Vita, maybe sometime later. Sony has no issue admitting the Vita is weaker than a PS3, I have no idea why Vita fans can't back off the idea. I, like many others, want to see a beautiful HD Persona. I want to see the series move forward in every way, including in presentation. Hopefully we won't be seeing a Vita multiplat because it WILL hold it back. The fact that Vita can play a port of every previous Persona game (except Arena, the only HD one) in no way guarantees or even suggests Vita being a multiplat console for it.
But literally all of this is speculation. Every single post. No one can guarantee shit, let's everyone just simmer down with the absolutes.