Once you reach Legend rank there isn't that much to do.
Maybe if you could or wanted to do one more /rankup it would delete all your claims, all your collector credits and all your $.
Maybe even all your items from your inv.
You would go from [Legend] to [HC-Starter].
Every rankup could cost 10x more and if you want even more hardcore every collector would need 20 votes instead of 2.
I can be really sadistic about these suggestions and one thing you could also do for hc players that they only get $0.10 for every ic they sell.
[HC-Legend] would be someone who has really worked for his rank, and not someone to mess with.
And I don't see a reason why this wouldn't work with donator classes too.
You could be [Royal HC Starter].
You would get all the benefits from being a royal, but you would also get other rank and pressure of getting better ranks [Royal HC Gamer] etc.
Also if these ranks would cost 10x the normal /rankup it would take money out of the system.
And this would have to be optional feature, because you really have to think twice do you want to give everything you have gained in last month (house, rm tools, quantum armor, powerflowers) just so you can do another /rankup.
edit: fixed a typo