Yes, totally possible. Right now extensions are data based. But there is another breed of extensions we're building towards, which is "previewers" or "renderers

Yes, totally possible. Right now extensions are data based. But there is another breed of extensions we're building towards, which is "previewers" or "renderers", which allow you to parse the text and display it in any which way. This will be coming pretty soon, and will replace the current built-in Markdown editor with an extension. Trying to remove as much built in dependencies as possible.