Thanks Stephen. Versioning, a markdown editor, granular permissions and core taxonomy + social tags would all be things we're interested in seeing in a replacement. In addition we're interested in social integration to the journal "Stephen updated the document How to Do Something Technical", magic words, links to a new page, etc.
More advanced features we've discussed might include; core workflow integration (DNN Professional), curation tools, social group integration (filtering), etc.
Do you have an ETA on your medium horizon feature set?
Also, feature sponsorship is certainly possible. We've done that in the past with module vendors. Please reach out to me directly via email (it's on my account here) and we can talk about what that might look like.