Well, depending on how the customisation bits work, I would assume clans can have some form of integration where they all wear the same colours/warpaint/clothes or similar to give them a uniform look.
Clan tattoos would be another step up - if you were really sure you wanted to play for that clan for a long time 
There are definitely some unique things you could do for clan integration though, have team only designs perhaps, or clothing you can unlock for your entire clan through winning controlled matches etc.
Its all a little silly and somewhat surplus to requirements, but it would be rather cool.


