With the release of the MACBOOK that runs OSX ONLY me i was sure since then that if apple will release an iPAD PRO will have iOS for sure?? wtf whats the point of macbook IF they intended to release an iPAD PRO with OSX?
from multitouch stand point OSX would have been a disaster, trust me, they had to focus for OSX to be for mac and for touch input...so double the effort and i dont think apple can and have the brain to deliver both segments perfectly. Even so they have bugs and some UI lag sometimes etc.
iPAD Pro is just the beginning..with iOS9 multitask in mind and the accessories but this is APPLE and we know they give us little features this year and little next year for the same device. So i am sure that with iOS10 you will have features like multi users accounts, and almost all the pro apps from OSX to iOS10 as well etc