In the upcoming StarCraft II patch, Patch 2.1, the classic StarCraft soundtrack is returning, and will be here to stay. Once Patch 2.1 is on your computer, you will be able to go into the sounds settings of StarCraft II and select which soundtracks (StarCraft II, StarCraft Vanilla) will play while you... play.
Patch 2.1 is currently live on the Public Test Realm, so if you want to hear the remastered classic StarCraft soundtrack for yourself, just look here for how to get on the PTR!
Source:
Battle.net - Patch 2.1 Preview: Classic StarCraft Soundtrack in StarCraft II
