So there is a
rumor going round that Atlus has Devil Summoner 4 in the works, which will a true sequel to Devil Summoner 3. Personally I think they might be jumping the gun a little since I can't see a Megaten game using realistic character models like the one in that scan but I guess it could just be promotional art designed to fool people.
Most people seem to be pretty annoyed about this and while I'd like to see the west get a game in the old Cyberpunk style as well, I'm actually pretty interested to see what Altus would do with a sequel to Raidou Kuzunoha. I think most people will agree that the original was a relatively flawed game. The atmosphere was wonderful and the cast was delightfully quirky but the battle system and adventure game elements were both mediocre at best. Atlus seems like the sort that learns from their mistakes though and if they managed to fix these problems DS4 could become something really awesome.
Of course, it will probably end up being some new IP and all this speculation will be for naught. Just as long as it isn't Persona 5.