So it sounds like the rumours of FFXVI being at the PS5 reveal event were false afterall, many games media people like Imran Khan formerly of GameInformer, Jason Schreier and ZhugeEx/Daniel Ahmad have said that XVI was not ever meant to be shown to begin with. Imran Khan even said every rumour he heard about "XVI" is actually what was shown for Project Athia, which isn't XVI let alone a Final Fantasy.
In a now deleted thread over on Resetera Jason said that XVI was not pulled from the show, and Imran, Jason and ZhugeEx all essentially confirm that.
However even aside from all of this, my own personal feeling is that the PS5 reveal should have been where FFXVI was revealed, the timing now was the time, like 2006 for FFXIII at the start of the PS3 era was, and 2013 for FFXV at the start of the PS4 era was, so even if FFXVI was never actually planned to be shown at the PS5 reveal, I still think XVI will be revealed before the PS5 launches, or at the very least I think that SE should reveal XVI before the PS5 launches.
Whatever Yoshi-P's project is I don't doubt it is FFXVI, even if he denied the recent rumours that state he is the director, he didn't actually deny being involved in it, only that the rumour stating he was director is fake, so he could just as easily be involved in it as a Producer or Executive Producer, and with that project having been in development for a few years now, even longer than Project Athia has been in development for, I think it could fit into SE's 2021 FY.
I'm not expecting FF7R Part 2 until at least 2023 at this rate, they've said they are still in planning for that only months ago and don't even know what they want to put in Part 2 yet, and it's not like they can reuse any location assets or anything from Midgar for the rest of FF7's world so it would take them just as long to make whatever location assets they need, and they still have to create entire systems for Yuffie, Cid, Cait Sith, Vincent and to finish Red XIII, which would take just as long to do as it did for Cloud, Barret, Tifa and Aerith once they had decided on the combat direction. The 7R team are also really slow, as is the KH3 team, especially compared to Lumionus Production/the FFXV devs who made much higher quality content in much shorter time, so I don't see FF7R Part 2 taking any less than 3 years to make, same for whatever the next console KH game is.
So the way I see it for 2021 what big game could they release from their Japan studios? Yoshi-P's project has been in early development since at least 2015 following Heavensward, and entered full scale development in 2019, by 2021 that's around 6 years of development which is plenty for a AAA game, the Luminous team also has started creating Project Athia's actual content in 2019 after they had done initial planning and setting the foundation for it in 2018, so that too could hit within the next 2 years given that FFXV only took 3 years and 4 months to make from scratch on Luminous Engine, while they were still making the engine at that. Whatever new console KH game is coming sounds even less further in development than FF7R Part 2 does, and KH3 itself already took 5 years to make on UE4, and FF7R took 6 years to make on UE4, both of which had heavy pre production matieral already created thanks to prior games too.
So I think FFXVI will be revealed before Holiday 2020, and could very well come out in 2021 or early 2022 hitting the 2021FY assuming it is actually progressed far enough in development, otherwise what other SE Japan AAA game does SE have?
So 2021 either FFXVI/Yoshi-P's project releases, or Project Athia does
2022, again either XVI/Yoshi-P's project or Project Athia
2023 FF7R Part 2
2024 next KH console game.
DQXII can slip in somewhere between those years too.