Following on from Dengeki Online's revealing review last week, Famitsu have posted a review for Kingdom Hearts HD 2.5 ReMIX, which releases in Japan on October 2, 2014.  In this review, it is revealed that the Kingdom Hearts HD 2.5 ReMIX Secret Movie "may hint to Kingdom Hearts III", and that there are contents related to the browser game Kingdom Hearts χ[chi]. 

This portion of the review can be read in full below, thanks to KH13 translator SkyKeybladeHero: