Famitsu recently had an interview with Tetsuya Nomura, The Kingdom Hearts series Director, to talk about the newly announced title in the series The Kingdom Hearts HD 2.8 Final Chapter Prologue! In the interview he speaks about the Battle System for 0.2BBS, as well as how the title will affect Kingdom Hearts 3's development. The interview also speaks about Kingdom Hearts' X (Chi)
Source: Thank you to KHInsider for the fully translated interview!
Famitsu's interview with Nomura about Kingdom Hearts 2.8