Wiki like functionality is something that could fit quite well to Nextcloud, and with the recent final closure of Hackpad on July 19th, see: https://hackpad.com/ maybe it would be time to adopt that project as a Nextcloud app? It has been open-source for a while after Dropbox aquired it, but with their push to DropBox Paper (https://www.dropbox.com/paper/ ), not too much further development happed. Never the less it is still worked on, see: https://github.com/hackpad/hackpad
While it can’t become a core app due to node.js dependency, it could never the less be a really nice addition to the Nextcloud ecosystem as it really fits into the overall collaboration idea, see:
As it is originally based on Etherpad (Lite?) maybe some of the code from Ownpad ( https://github.com/otetard/ownpad ) could be adapted and this : https://github.com/rschiang/taipad might also be helpful.
Edit: There is also a Fork called Stekpad: https://stekpad.com/ (actually not so much a fork as the project still developing it).
Edit2: http://jimmyb.ninja/post/1447447641 for installation. Also see: https://www.reddit.com/r/selfhosted/comments/527674/hosting_hackpad/?st=j5d4st2q&sh=6e6c98bf
An short term alternative could be modifiying Ownpad to use this wiki like Etherpad plugin: