Will the Japanese version RWBY remake the animation or just be changing the voice actors and actresses?
I have compared the animation and dialogue in the English and Japanese versions of the first episode of RWBY ("Ruby Rose"). The dialogue and voices have been set to match the flaps of the character's mouths rather than the other way round.

The dub is purely audio, no animation changes were made. This is typical of most localisation dubs both in the western world and in Japan also.