FFVII:R is never coming to Switch. It's "First on PS4" Sony has full timed exclusivity for the foreseeable future. Until all parts are out on PS4 it's not going anywhere. And the more likely scenario is that it's going to be PS4/PC only. Sony has their hand in it. People need to keep their expectations in check. This one is not happening.
As for KH3, that's possible since it's already on Xbox but the issue with that at its current state it would break the Switch because it's too weak. It's pretty much a slightly more powerful Wii U. Unless they severely downgrade it it's not happening.
I know people keep making that "UE4 scalable!" excuse but that's not how it works. My phone can run UE4. The Switch being able to run UE4 means jack shit. It uses a mobile processor and mobile chip. Come on guys.
Is it possible? Maybe. Is it going to happen? Probably not. It's the same with FFXV. The game is simply too powerful to run on this system. Expect more low end ports of FFXIII or something or mostly 7th gen 3rd Party games. This system isn't getting any graphically extensive AAA 3rd Party support from this generation. So stuff like FFXV, Red Dead Redemption 2, The Witcher 3, etc. You should pretty much rule out of every single major AAA 3rd Party game.
Again, keep your expectations in check. NIntendo fans do this to themselves every generation and you just end up back at the start. Being a Nintendo fan since the beginning I understand what you go through but please keep your expectations in check. Predict and ask for things that are likely to happen. Don't ask for the impossible because you will be disappointed at what's actually going to happen.