I agree with pretty much everything, except designers using Git. Sadly, Git doesn't work for PSD files properly. Some of the PSD files I've worked with before (900mb+) for larger websites and applications would definitely not be a good fit for Git. Although I think the blame lies mostly on Photoshop's end not being the right tool for web design, but being used by designers anyway. I think whatever tool ends up replac…
Many designers who do not code at all do not understand the workflow of Git. The process of pull, commit, push is extremely confusing. E.g. One large company that forces all designers to use Git ended up with multiple files with slightly different names in the repo system. Designers do not understand the concept of merge conflict and will just rename the file so that they can push to the repo. Case in point: the mental model of Git has worked well for developers, but does not translate well to non-coders.
Overall, I think a version control system for designers should be transparent, non-intrusive, and just works. Designers should not have to worry about when to push or pull, should not have to worry when to commit. I think it should just backup every saves and then subsequently allow them to flag specific design iterations that they want to highlight.
Disclaimer: I am co-founder of Pixelapse - Version Control for Designers.