You think 3DS can handle that lol. I doubt the Vita could handle that. I have said before Persona 5 is going to be on a console not handheld.
Yes Atlus are going to forget an engine they have been developing for years so they can develop on a new platform with no pre existing fanbase.
P4G sold 260 000 making it already the second best selling Persona game of all time. I would agree that the Vita would be a poor choice if P4G did not do so well. I still think P5 will be only on consoles though.
A collaboration is not going to make Atlus suddenly forget the financial implications.
The thing is the Vita is a Playstation console so they know soem of there base would be there. WiiU is not a Playstation platform and its bombing. The last paragraph is nothing but wishful thinking that Nintendo money hats them. Persona 5 would not move any WiiU units because 90% of sales will be on PS3 as thats where the fanbase is.