Hmm if they did
Master Xehanort - final boss theme?
Ansem - Forze de Male remix
Xemnas - Darkness of the Unknown remix
Young Xehanort - Dark Impetus remix
Xion - Vector to the Heavens remix
Vanitas - Enter the Darkness remix
Terranort - Dismiss remix
Marluxia - Lord of the Castle remix
Larxene - ????
Luxord - ????
Xigbar - ???
Dark Riku - ???
Saix - ???
I suppose The 13th Dillemma, The 13th Struggle and The 13th Reflection could go among Larxene, Luxord, Xigbar and Saix. Maybe a The Other Promise remix for Saix? Dark Riku could have Another Side remix
My picks would probably look like:
Master Xehanort - Forze dell'Oscurita
Ansem - Guardando nel Buio
Xemnas - I'd actually really be all over Disappeared being used, but let's be real, it'd probably be Darkness of the Unknown
Young Xehanort - Dark Impetus remix
Xion - Vector to the Heavens remix
Vanitas - Enter the Void remix
Terranort - Dismiss remix
Marluxia - Lord of the Castle remix
Larxene - 13th Reflection
Luxord - 13th Struggle
Xigbar - Another Side would actually work pretty well here.
Dark Riku - Forze Del Male
Saix - 13th Dilemma
I'd hope they'd be new arrangements, though I'd have no objections to the 1.5 arrangement of Vector to the Heavens being reused. That version is perfect as is.