Since no one actually replied to OP that I saw in my brief skim... I will. This is from the POV as a desktop user who does CAD work on large monitors.
I think Windows 9 will be accepted. I think the new hybrid start menu that i've seen floating around will bring in desktop users while still allowing Modern UI apps to be discovered and easily accessible without having to interrupt workflows by bringing in the full screen start menu.
I think this will also help ease the shock some users have when moving from 7 -> 9:
Users running Threshold on a desktop/laptop will get a SKU, or version, that puts the Windows Desktop (for running Win32/legacy apps) front and center.
I kind of like the look of the screen posted here (if it's real):
http://www.neowin.net/news/windows-threshold-the-modern-ui-takes-a-backseat-for-desktop-users
Now back to the Windows 8 arguements
Honestly, 8.1+ didn't bother me that much. Booting to desktop, being able to pin Modern UI apps to the task bar, and the other desktop friendly tweaks (right click the start button!) made for a much better workflow. It also was annoying when you wanted to shutdown your PC prior to 8.1. Not hard, just annoying that the graphical way was buried. I think ctrl-alt-delete still worked, but I barely used 8 prior to the 8.1 update.
Talking about hitting the Windows Key and just typing... that might be fine for people like us, but even I sometimes have to stop and remember the name of the program I want to run. I end up just adding it to the desktop task bar or the full screen start menu. I found it easier sometimes to just hit Windows Key + click 1 icon than Windows Key + typing. Usually not the case, but sometimes. That, or pinning to task bar so it's just one click away.
But now we get into my parents, who can use a computer to start a browser, use facebook, some word processing. They are trained to find the icon they want and click it. They don't know the name of every program installed, mostly just the icon that represents 'the internet' or 'to type a letter'. Plenty of people trained to click icons and not have to worry about what the program is called. They struggled with the Windows Key. "Why can't we just point and click?", "What if we don't know what to type?".
Perhaps they should learn these things. But they don't care to learn them. They just want to get on Facebook or e-mail. Don't get me started with trying to teach them the new way to shutdown the PC (pre-8.1+). Even after 8.1, mom still likes to fight to bring up the charms bar click several times to get to shutdown. I have to remind her there are easier ways now.
These are just my personal experiences. I can easily adapt and it doesn't bother me. I do still however run Windows 7, and will do so for sometime. I also run Arch Linux on several other boxes, so fixing things and change isn't that hard to me.
