Please (please!) don't quote me on this, but-
I'd totally expect some modicum of a rebalancing pass greater than what we've seen in KH1HD, KH2HD and BBSHD.
Historically, in the Kingdom Hearts series, you've had:
Remakes - going from one format to another, e.g. CoM -> Re:CoM, 2D -> 3D, etc
Remasters - Simply taking the same assets, sprucing them up, touching up for widescreen, etc.
From what we've seen of DDD HD, it's neither the former nor latter. It's using the same assets so it doesn't count as a remake in the Re:____ sense, and it's not just a remaster since many game systems need to be changed to accomodate the transition from 2 screens to 1, the least of which would be the UI. This is a far bigger change than e.g. rebalancing BBS's Mirage Arena because multiplayer is yanked.