There are no plans at JustSystems to create a plug-in for the DITA OT that would allow you to generate output compatible with a particular Wiki.
One option would be to approach the DITA Open Toolkit project and make a feature request. The project is here: https://github.com/dita-ot/dita-ot
Keep in mind that there is no single standard for Wiki "markup", so a plug-in for the DITA OT that would generate such output would either need to be flexible and configurable, or you would need to target one or more particular Wikis. See: https://en.wikipedia.org/wiki/Wiki_markup
Another option (I'm guessing it is likely the best option
) would be to find out if the particular Wiki being used supports an import feature, or whether it can be configured to support one. The most likely type of file format that could be imported would be HTML, and the DITA OT (obviously) can generate that. See: https://www.google.com/search?q=import+html+into+wiki