Last week a Pachinko site wrote an article about consumer announcements of Pachinko machine and that Persona 5 is scheduled for Sony's PS3 was leaked out. However, a few days later they removed that part from the article (Playstation 3, [Persona 5]) and we didn't got any explanation of it from Atlus Japan nor did they denied the announcement.
We have seen this before with Tales Of Vesperia and Star Ocean 4 which were scheduled for Xbox 360 when the announcements recently leaked out and got removed a couple of hours after. And Persona 4 for PS2 from Bloomberg's financial report.
Even if we don't have any official announcement from Atlus Japan yet we can probably guess it's set for PS3.
Shin Megami Tensei Strange Journey's mystery platform ended up to be DS. All spin-offs are mostly on handhelds and that have been the case with Last Bible and among other titles on Nintendo's handhelds. Check the Shin Megami Tensei library.
And I doubt we will see SMT IV this gen because SMT III: Nocturne took two generations before they made the third installment in the series. If you own a Playstation 3 you have to look forward to the Persona series as what Atlus Japan did focused on back in the PS1 days when SEGA Saturn got its own share of the cake which was Devil Summoner. Atlus is not only about Persona they have tons of series to stick with unlike other software houses.
http://www.qj.net/Pachinko-site-ment.../49/aid/133242