It's never ever ever ever going to happen.
I wouldn't exactly say never, if Square makes 8 - 10 million sales off of FFXV in lifetime sales, I wouldn't put it past them to try and force sequels out of it, but the only way that could be possible is if they semi-reboot the entire thing which is possible for them to Type-Next FFXV but I don't know about that.
I mean a trilogy of games using most of the assets that are already made reducing the costs, and can be made with reasonable development time, along with the demand being there, I don't know I think it's possible, granted if it does happen they would have to tread lightly. They can't make this the Versus XIII that the original one was, or else people would think that Square Enix cheated them, but with how FFXV turned out whether people will feel that way I don't know. It would have to be marketed as a sequel(Think Type-Next I put an idea on the Tabata's vision post), Versus XIII/XV 2013
"I think a sequel of FFXV could work in sort of a Final Fantasy Type Next or Type-0 kinda way Spoilers for those that haven't played Type-0 yet(I recommend the HD version if you are into ARPGs)
Type-0 ends with everyone dying, but there are two alternate endings one where a woman named Doctor Arecia Al-Rashia is a fal'Cie that oversees Orience, she removed the Crystals from History resetting the timeline in one timeline the Crystals are removed from History which allows Ace and his friends to live normally, the other one is the Type-Next teaser. For FFXV, I suggest bringing back the fal'Cie to reset the timeline of FFXV to use it as an experiment to find the gate of Etro, or Etro rewards those involved curing the Starscourge caused by Ifrit, by sending them off into a New World, a new timeline, reincarnated into a world of a Versus Epic. So basically both my ideas are soft-reboots, and this will spawn 3 full games using the assets of FFXV, and whatever is left of Versus XIII FF Versus XV-1, Versus XV-2, and Final Fantasy Versus XV: Final boss should either be a fal'Cie, Etro, or Ardyn again(Loved him as villain he might actually be my favorite yes more than Kuja, equal to Sephiroth) The Final Chapter.I think the gate of Etro idea would be better because the fal'Cie are dicks that view humans as nothing more than tools to achieve their goals, so it could work better that way, I don't think Etro would exactly have a reason to resurrect Noctis.
So the way I'd think of it Final Fantasy XV would be like Type-0, a Versus XV(or XV-2, or XV-Next) would be like Type-Next(which seems to be in an alternate universe)"
In order for a Versus XV to not produce massive salt and backlash they would have to
1. Make it seem like a sequel, while being a reboot, so it being an alternate timeline has the be stated and made clear within the trailer like they would have to show the world of Eos being recreated by the fal'Cie, make it clear it's an experiment to find Etro's gate which caused them to recreate the World of FFXV after FFXV's ending of curing the Starscourge.
2. They would have to show off how it's different from FFXV, so fal'Cie, and Etro would have to be at the very start of the trailer if they were to make one, then they would have to splice in some FFXV 2013 footage, and I mean very few things like young Noctis running with Young Stella, the scene where they see each other(but it would have to be altered), they could only show parts of the citadel escape fight, but they would then have to show something completely different like the Chocobros fighting a fal'Cie, they could use the stand off scene with Regis but very briefly, and the people of Eos worshiping Etro.
3. They would also have to make it clear that this will be a trilogy, and each game will be as full as Final Fantasy XV granted if the FFVII Remake does good people might have more faith in Nomura and Square Enix again, so it's possible that people might be more trusting of the multi-part format.
4. It also needs a release date, a solid release date in that trailer.
