Square Enix's Osaka studio is looking for UI designers, effect designers, and technical artists to work on the "HD development of the Kingdom", resulting in many fans speculating on what that could mean.
This news comes from Gematsu, and they refer it could be linked to a new game. While we think that's, of course, plausible, the "HD development" part makes us believe it might be instead linked to a new remaster project. Considering the entire series has been remastered on PS4, that leaves PC, Xbox One, and Switch on the table, but from the three, Switch seems like a much better fit, considering a few Kingdom Hearts games were already released on Nintendo consoles.
This is, however, pure speculation, so don't take our word for it. Regardless, Square Enix is definitely working on something related to Kingdom Hearts.