Great topic!
So here goes my wishlist:
1. The Strings made Complete (Solo, Chamber, Orch & AP). And I mean all the things that are still obviously missing, either in this family or that.
2. A full collection of contemporary techniques & expressions for every instrument, aimed at soundtracks and modern composition in general.
3. Various "Lyrical Sustains" for most (all?) of the solo instruments. Most sustains are rather "clean" which is good in many cases, but uninspiring in other.
That's about all I can think of now.
Cheers,
Alex