I personally responded with over $1000, just because I really hope Apple decides to go after the Surface Pro market.
Going based off entirely what I want, not really what I think Apple will do here, but imagine:
Digitizer with 1024+ levels of pressure sensitivity (artists can then use the Pro for sculpting, digital painting, etc).
Full OSX support (Otherwise you have to wait for the device to come out, and then wait for companies like Autodesk and Adobe to make iPad Pro specific ports of their products (or even worse, use the lackluster products available on the iOS App store).
Attachable keyboard a la the stormtrooper style iPad cases that were out (they essentially made the first and second gen iPads look like Macbook Pros).
Obviously this would compete against their current lineup of products (I'm sure the Air would still sell, and most definitely the MBP.. but honestly, if they didn't update to have touch screens as well then I could easily see the Air dropping in popularity substantially).
Honestly, I just want an iPad with an active digitizer. None of the stylus or pen options work on the current iPads (and not for their lack of effort, there's just no way to do anything other than sketch or basic drawing; and that's a real shame. Digital art is amazing on my buddies Surface Pro 3, but it would just be that much more amazing on an iPad Pro I'm sure).
Sorry for the rant, first post in seven years.