Instead of a new Air, I'd rather see an "intelligent keyboard" for the iPadPro that can turn it into a full macbook.
Something like the HP-TC1000 I owned 12 years ago. It was like having two complete different devices. "Pen" mode was great to write some meeting notes or for doing creative work. Attaching the keyboard gave full access to all full OS features. Totally simple and beautiful.
I don't care if iOS and OSX get integrated or not but would really love to just get a single device supporting the two distinct use cases. With a single set of accessories (power, keyboard, adapter cables) and Apple ease of use, performance and quality.
http://pencomputing.com/frames/tpc_compaq.html