Creating different page item types, and plugins, based on how an item is edited rather what the content is, is the road to needless complexity. To maintain simplicity a better approach would for different content editing mark-up to be supported by making the editor into a pluggable component.
There are already a number of variants of the 'text' page item. With the original 'paragraph' item having been joined by 'html', 'markdown' and at least one other wiki markup (that is known about).
This diversification can result in content not being visible when accessed from different origins, users needing to be comfortable with editing in a range of different mark-up (if their site has the required plug-in), and site owners being both sufficiently technically/security literate to review any new plug-in before possibly installing it.
# A better approach
For text items it would be better to have a single item type - the text would be stored with standard way (a minimal HTML subset is suggested, so standard libraries can be used). The user should be able to select the type of mark-up they prefer to use, and be presented with an appropriate editor.
The editor would round-trip the content from the stored content to the mark-up used for editing and back. For example a markdown editor could use dr-sax and marked to perform the round trip conversion, see github .
Other possible editors could provide an experience more like medium.com