I like the idea. I personally have been wanting to switch out a few songs and replace them with ones from FFXI(Like The Black Shroud with Zi'tah and the battle themes with any other battle theme).

Nothing against the current soundtrack but I think far to few tracks were spread between to much content(mainly because of the massive zones in which 2-4 songs would normally be in place in any other MMO without zones this large) I don't know how likely this is to happen though as much as it disappoints me to say. Though on the other hand SE has been listening to other ideas that are far worse then this so maybe there is a chance.