Kingdom Hearts co-creator Tetsuya Nomura has recently acknowledged the possibility of retirement alongside whether or not to bring the action-RPG franchise's story to a conclusion.
This comes via an interview from YoungJump (thanks, VGC), during which he was asked about future plans for Kingdom Hearts. Nomura (53) responded by stating that he only has " a few years left" until he potentially retires, and will need to decide whether he brings Kingdom Hearts to a conclusion before this happens.
“I only have a few years left until I retire, I have to decide whether to retire first or finish the series first. However, I’m making Kingdom Hearts IV now with the intention of it being a story that I will complete.”
We can only guess at what Nomura is implying with the comment regarding Kingdom Hearts IV, but our assumption is that he simply means that it will serve the overarching Kingdom Hearts narrative and lead to a hypothetical ending.
Nomura has served as director on every Kingdom Hearts entry since the franchise's inception in 2002. It would seem somewhat odd, then, for the series to continue without his involvement. However, it's possible that Nomura may continue working on Kingdom hearts well beyond his retirement age if he feels that there is a potential story worth telling.
For now, Kingdom Hearts IV is not officially planned for release on Nintendo platforms, but we'd be very surprised if it didn't show up on the upcoming 'Switch 2'. A previous reveal from the now-ousted leaker known as 'Midori' stated that the game "might" show up on Nintendo's next major hardware.