There are only three instruments I want to see. Nexus (never happening according to ReFX), Virus TI Polar (most likely never also), and a Nord Emulation (Discovery Pro would do with a cleaner interface).
The only other thing I would like to see is more support for NN-XT and a sample round robin feature.
The NN-XT is the perfect sample player. Just not enough support. Lets get EXS support or something.