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.
Wii U is a GCN 2 - I called it months before the release!
My Vita to-buy list: The Walking Dead, Persona 4 Golden, Need for Speed: Most Wanted, TearAway, Ys: Memories of Celceta, Muramasa: The Demon Blade, History: Legends of War, FIFA 13, Final Fantasy HD X, X-2, Worms Revolution Extreme, The Amazing Spiderman, Batman: Arkham Origins Blackgate - too many no-gaemz :/
My consoles: PS2 Slim, PS3 Slim 320 GB, PSV 32 GB, Wii, DSi.