Several job listings for Square Enix lists the development of a Kingdom Hearts project.
The listings for the Osaka area request UI Designers, Effect Designers, and Technical Artists to all work in First Development Division. Each job listing also mentions the work is to be used “in HD development of “Kingdom Hearts” series.”
Under the Effect Designer listing, Necessary Skills and Experience include “Effect data creation experience in PlayStation 4,” along with “Unreal Engine 4 basic operation, Unreal Engine 4 effect tool cascade operation experience.” This may indicate that the project is not in development for the upcoming PlayStation 5.
It is worth noting Kingdom Hearts III switched development to the Unreal Engine 4, which may suggest additional Kingdom Hearts III DLC is in development, as opposed to a new game. The Re:Mind DLC is launching Winter 2019, so it seems unlikely that the need for those particular roles is for that; being it is so close to its release.
We will keep you informed as we learn more.