All in all I have to say I'm not particularly concerned with KH4's development. Most of Square's colossal fuckups and handicaps in their management have died down considerably around 2017-2018. They now have their house in order, so to speak, thanks in no small part to Naoki Yoshida's influence.
Another thing to consider is that in this gen, Sony, Microsoft and Epic are pulling ALL the stops to making game development faster, easier and more efficient. Nintendo can suck a dick, though.
If anything at all poses to be a hindrance to KH4's development, then it would probably be either Disney making bullshit restrictions (something they do far more harshly with their more recent works) or the FF7 Remake taking up Nomura's time.