I think the most difficult question are going to be how do you constraint that core feature without ever wanting to add more to it? For instance, collaboration

I think the most difficult question are going to be how do you constraint that core feature without ever wanting to add more to it? For instance, collaboration is a huge topic. You can have coding collaboration on the file, and that would be basic and appropriate, you can then replicate slack and you'll have chat rooms, which is entering creep territory, but it's natural! Then soon the chat room will need to link with issues and you can now have TODOs linked to some kanban board and we should be able to speak while we code on the same file! And this goes on and on. It's exceedingly rare that the organization found hard courage to specifically avoid features that looks like easy pickings for the purpose of avoiding them.