Theatrhythm Final Fantasy is a rhythm-style Final Fantasy title for the Nintendo 3DS. The producer of the title, Ichiro Hazama, has participated in an interview with Siliconera where they mention an interest in making a Kingdom Hearts title of the same genre, and also explain how Theatrhythm Final Fantasy's art style draws inspiration from Kingdom Hearts Mobile. You can read these parts of the interview below.
From the beginning, we were discussing how to present characters from the entire Final Fantasy franchise. When we saw the designs of the Final Fantasy guest characters in Kingdom Hearts Mobile we thought this is going to work.
--Do you view Theatrhythm as a series now? What series would you want to work with… Manarhythm? Theatrhythm… Hitman?
[Laughs.] Personally, I hope this will be come a series, but Theatrhythm Hitman will probably be really far off. There are many series that I would want to work on for Theatrhythm. Dragon Quest has a lot of music and Kingdom Hearts would be wonderful to do if it’s possible. I’m not to familiar with the Eidos collection, but Tomb Raider has a long history so it must have a great collection of songs. That might be fun.