Our first priority will be to migrate the site as fluently as possible to whatever CMS we transition to. Archiving it as HTML and starting from scratch with a new platform — that's a last ditch effort, I think.

[Edit: I tried to cover the WP fork subject here]

Hugo as a longterm solution isn't going to float with some of our users, I'm afraid. I can vividly imagine somebody turning the old site into a single "Hello world!" page given that kind of permissions.

We will need strictly limited access for contributors, and a clear, friendly input field for text...