Eventually we might get a whole GM Rompler with many of the instruments. For the moment here is a collection of instruments covering the first 3 categories Piano, Chromatic Percussion and Organs with 24 instruments total. Many new instruments and lite versions of things like the Salamander Piano. Lots of cool instruments from Sam Gossner's new VCSL project.
Aspen GM Soundset Win 64 Win 32 Mac AU MacVST
Note that Reaper and some other DAWs don't like Maize Romplers
See read me for individual instrument licenses, all can be used to make commercial music.