that is huge ammount. we willllllll neeeeeeed moding for soundtracks fooooooooooooooor sure. It is like 150 mbs.
.
But one thing for sure they will work in awesome way. Just make lot diversity please(scary/horor/romantic/chillout/Dubstep/jazz/classic/native/electro as example) (I think skyrim gives nice ideas)
for diferent sitsuations,
like 3 for each biome:
mountains
plains
desert
forest
tundra
cities
for actions:
under attack, after it, swimming, flying
for places:
tunnels, dangerous areas...
you get idea.(I think you have lot clearer idea than me anyway).
And I will be happy to hear what you will make.
(is there ambient dubstep?)