Originally Posted by
Meow_Zedong
They won't erase all of Uematsu's tracks, it makes up most of the soundtrack.
The original soundtrack was around 70-ish songs, all done by Uematsu. Not all were in the game at launch, most were just waiting for future use, like the event songs.
So the patches that introduced new tracks to the game were a combination of unused Uematsu tracks and completely new music, composed by SE's in-house music team (Naoshi Mizuta, Ryo Yamazaki, and Tsuyoshi Sekito).
The new music team's contributions have only been around 20 tracks (and a few remixes of Uematsu songs), so the soundtrack is still mostly Uematsu.
For those that are curious, the VAN Darnus battle track is Uematsu (at launch it was the theme to Coerthas leves, but they changed it), but the DEUS Darnus track (2nd phase) is the new music team. Garuda theme is also from the new team.