I'd love to see is a Reason instrument designed to work like the Yamaha VL-70m or the Wallander Instruments VST's.
The goal is very small, efficient playable instruments with the expressiveness and behavior of a real instrument (and compatibility with wind controllers).
Anyone that's ever played a sax through a sampler is aware of it's shortcomings. Even with a wind controller, it just doesn't sound right.
Create this and I'll be the first one in line for the Reason Jazz Band refill.
Check out the Wallander Instruments site for an idea of what is possible. I've heard an early sample MP3 of some saxes being played through via software and it's by far the best sounding virtual sax I've heard to date. (The woodwind instruments are coming out soon. Right now they just have the brass section up).
I believe this will be the future for reproducing real instruments, as it doesn't require a lot of overhead, there are no huge sample libraries required, and the instruments are a lot more expressive (when played live) and natural sounding.
In the event that this idea doesn't take off, put me down for 1 order of a high quality hyper-sampled Reason Saxophones refill please.