Kingdom Hearts 3 isn’t being worked on by the original Kingdom Hearts team. Series creator Tetsuya Nomura himself is busy on Final Fantasy XV.
Instead, Kingdom Hearts 3 is being developed by Square Enix’s Osaka studio, the publisher revealed this morning at a Q&A. The Osaka studio worked on Kingdom Hearts: Birth by Sleep, Kingdom Hearts 3D, and are also working on Kingdom Hearts 1.5 HD Remix.
Square Enix also confirmed that, like Final Fantasy XV, Kingdom Hearts 3 makes use of Direct X 11.