Persona 5 G will never come exclusively to 3ds or the next Nintendo handheld. You wanna know why? It's Atlus' record. Just look at how they develop their games - they ALWAYS go by the route of the lowest development costs. They went PS2 -> PSP even though PS3 has been already out for years. When PSP started dying, they went PS2 -> PSV. Now what are they doing? Oh, the take a 3DS game (EO) and are just reskinning it and calling it a Persona for 3DS. They are reskinning a PSV game (Miku? The dancing game) and calling it a Persona for Vita. Now with the PS4 raging, they still go with PS3. What does this tell us? That they are gonna invest a pile of money into porting this game into a totally new platform with a totally new architecture? Or are they just gonna port it to Vita, with which they already have experience, which is similar in power to PS3 and considering it's said to be very easy to make PS3 into PSV port.
I believe the answer is simple. Atlus doesn't like to waste money on development, as that cuts directly into their profits and with their sales they don't have much room for error. Moreover Vita will be the shit in Japan come 2015, so I can't see any single valid reason why anyone would argue against it, except for just trying to annoy the fanbase.
Trying to annoy the fanbase? Atlus Record? C'mon your points are very good to say it'll stay vita exclusive(or sony in general) but its not set in stone. Many franchises were in the same situation and yet have been proving overtime that basic logic=/= future outcome.
Somebody would of told you FF would be multiplat with X360, you can use this argument... Proven false
MH was huge on sony, yet its exclusive to nintendo, including a new gen (MH4).
Persona 5 will be on ps3 and its easy to see why. To say its impossible for persona 5 to be ported/remade for ninty next gen HH is silly now. Trust me, Just look up MH threads/articles back in 2010-2012.
Beside, it could be multiplat if anything. Vita migt be big come next year, but who knows if it'll outsell 3ds. Beside 3ds has a 15.5mil user base vs Vita's 2.7mil, so it kinda doesn't matter if one sells better than the other come next year