The new version of ESB in 5.1 (with Bluray-derived LFE and improved surround decoding) already exists, and can be found on v2.0 of the Despecialized Edition. It will also appear on dark_jedi's new release when that is completed. A new version of RotJ is also on the way.
I haven't released the audio tracks separately yet because I wanted to put them together in a collection when they're all finished.