“Kingdom Hearts is Sora’s story, but the series in development now is also another character’s story,” Nomura replied according to a Famitsu interview transcript. “So to speak, that character is the focus of this series.” Famitsu asked about the “this series” bit, but Nomura couldn’t say anymore.
Nomura said there will be another “mystery” title that ties the series together. Wonder who is the star of the spin-off. Ansem, maybe?