The easiest thing I can think of it is the possibility to change the username against 500 Merits from the points that you acquired.
in other words, whenever you gain 500 Merits you can change the name for once.
Changing username like that wont be a bright idea but if the admin has the time to code then he can allow users to add
custom title if they are spending merits and it will be another interesting factor for users who are having a ton of merits and people would like those challenges to keep things interesting.
So, of if i have 500 merits i must spent that merits of i want to change name ?
What about the rank ?
It will impact your rank too if you are not having enough merits if it is implemented and hence it will be a rare credit for users who are dedicated to the forum. Once again allowing people to change the username is not a great idea but it can be allocated for custom title.