Current wiki-code editor has some scripts written for it. Might be as simple as a button that does something with currently selected wiki-code. Will you be making hooks and tutorials that will allow easy creation of a user-scripts?
I'm asking because I was just trying to extend VisualEditor and it took me something like 2 intense days of digging to be able to simply add a button. Even worse. I didn't really found a way to nicely hook into on some on-ready event. I had to overwrite (proxy) one of methods of existing classes (specifically I had to wirite a proxy for `ve.ui.FindAndReplaceDialog.prototype.onFindChange`).
VE docs are nice I give you that. But they lack recipes... Or maybe I missed them. Good thing docs are linked with source code. Helped a lot when I noticed this...
So to conclude - if you are going to replace current editor please add in-docs examples of hooking into the editor toolbar and such and please add hooks for user-scripts.