I'm against it in all ways. I'd much rather have a KH3 sooner than another game to stall and take away from it. Even more so now that we're getting collections and gathering the games together. Another game would ruin that as well by spreading it.
There not endless the possibilities are limited to those things and there things that don't really need scenes cause we know what happens. Xehanort is Aporentice for a year or so and messes it all up, throws Kairi into space, etc.
Those aren't unexplained thighs needing scenes or elaboration cause we already know.
Dark Realm has a different flow of time and since Aquas not aged much or any then there's not much to really cover there.
Plus it wasn't Nomura that closed the bbsv2 thing but higher ups. Even if he'd like doesn't mean he will or can. Most the games are ones he didn't even intend on.
To me, anything of truly important info, can be included in KH3.