Sure, you can commercialize any of your plugins/exporters as you like. You'll probably run in to problems trying to sell plugins in C2 though - they're just text files containing javascript, so preventing copying is basically impossible. However, you could sell exporters or the server-side part of a multiplayer plugin.
I'm not worried about any plugins/exporters competing with official ones. In fact, if your multiplayer plugin is good and there's a free edition of the client-side plugin, I don't see why we'd need to write another when we could just promote yours. If you go ahead with this and want to collaborate in some way, shoot me a message and we could try to sort something out.