A little while back I requested some kind of Augmented Drums/Percussion instrument which is still something I feel will be incredibly useful.
Though, in the case world instruments, I don’t think you should stop at Yangtze. There are many other rare and exotic instruments from across the world that I feel are worthy of their own instrument. Especially with a a cinematic focus on them.
Processing them and playing/ramping them through different resonating bodies to create “unheard of” variations would be another thing that would be fantastic to see done. Often in the world of film, tv or gaming we are wanting instruments to sound alien, or as if they were from a fantasy realm. Still musical, but more exotic and unique sounding.
I feel this is something the Augmented series could do well at. Reamping samples through different experimental structures could be a great method at adding extra value as you upgrade the Augmented Series going in to the future.