There was talk of them being put in to a game or something; but it was never put in motion AFAIK.
As said above, if someone with miniranks scams, the victim can request the miniranks to make up for some of the loss. Otherwise, the banned member may return and removing the miniranks would kind of contradict the "other stipulations" in pardons - in the way that funranks etc are not removed upon unban (generally).