I wouldn't mind if there are new ranks added but I don't see how it could be beneficial (for the users and/or the forum).
You propose news ranks but you don't give arguments on why they should be added and it's the most important thing you should have mentioned.

- For fun? There are a lot of better things to do here to get fun.
- To make less high-ranked users? With time, the situation will be the same, and so the forum will need again to create new ranks X years

mega, ultra, super are not very innovative as name