I would personally imagine something a bit like Sublime, but where all the "plugins" were actually just code contributed to the central codebase, and delivered by updates. (Specifically, I'm imagining it would work like Cloudflare's https://github.com/cdnjs/cdnjs for plugins.)
Given that the editor would then have "everything" in-the-box, it'd then probably have to have emacs-like modes, as well, to allow all the plugins' various key-bindings to live together.