ATLUS usually goes for the most popular platform at the time. That's why they went from PS2 to DS to 3DS. They also LOVE to reuse assets, which is a good sign for PS4 because of all of those beautiful HD demon assets used in Persona 5.
I'm guessing that SMT V will be for PS3 and PS4. It'll be cell shaded with minimal production values, and it will be very anime to capitalize on Persona 5's worldwide success. It will have less demons than 4F and a worse story, but it will be the most successful game in the series.