The Square Enix Music sampler from Tokyo Game Show 2014, titled Square Enix Music Sampler CD Vol.9, has revealed that the official soundtracks for both Kingdom Hearts HD 1.5 ReMIX and Kingdom Hearts HD 2.5 ReMIX will be released in Japan on November 26, 2014.

Previously, these soundtracks were teased as Kingdom Hearts HD ver. Soundtrack, but they are now known to be releasing individually, rather than as a single package-- so, look forward to Kingdom Hearts HD 1.5 ReMIX Original Soundtrack and Kingdom Hearts HD 2.5 ReMIX Original Soundtrack on November 26!

Thanks go to @jkermarrec for the tip.