As far as something like Smash goes, I don't really see it. Any 3rd party is going to have limited implementation, and as far as SE's goes, having chosen FFVII twice already, it's going to stay there. I don't know just how the adquisition of liscences of use go for the 3rd party stuff, but I would guess they can't just include even 1 or 2 elements of a second property since you have to pay full cost of use or something. So it's best to just stick with one property and use lots of stuff from that. Who knows.
Kingdom Hearts is another good chance. I mean, Neku is there, seriously wtf (except KH3 is the last one I think? I'm not into the series so I'm not sure). Then also get it on Switch.
It could be, but unfortunately chances are quite slim. As Nomura himself stated in this E3, as KH got more and more original elements, it made the use of their pre-existing properties less of a need to have. And it shows.
The first game had ample Final Fantasy prescence, but if you notice, it's also the game that had the least original elements. It was just the Destiny Islands trio and Ansem SoD for the most part. In comparison, you can see a big relevance drop in KHII. The Destiny Island FF crew only get a single-scene cameo at best, and mere mentions at worst. Twilight Town introduces more FF characters, but their roles are quite minor, as it's the OC characters that get more focused on. Only the HollowBastion/RadiantGarden FF characters retain some relevance, but it's lesser in comparison to the first game.
Dream Drop Distance having the TWEWT crew is likely since the setting finally had less of an OC prescence than previos games. They're there, alright, but not in the main portions of the games, hence SE fially adding something of their own again. As it is, chances don't look good for KHIII having much pre-existing SE properties, if at all. Some people even doubt the Radiant Garden FF crew will appear even if the world does, since just like how they weren't included in Birth by Sleep, the original elements are too much it could make things too convulated (Too convulated? In KH?
).
Not all hope is lost, though, since the franchise as a whole doesn't seem to be above cameo and/or standalone appearances and the like. And by the way, KHIII won't be the last KH game. It's just the last of the whole "Xehanort Saga", as it's called. As it is, I wouldn't discount some Chrono prescence in a future KH game, or even in KHIII itself. But chances overall are slim.
