I don't really see a system such as this being a huge help. I feel that growing the user base, building out new categories, and the passage of time will decentralize power slowly but surely.
I do think systems for disputing flags and abuse could be developed, but Steem Power should never be removed from an account.
Any penalty that may be imposed could be on future earnings only. All rewards would go toward clearing the negative judgement, forcing the user to work off their debt with positive posting & curation in order to resume growth of their own balance.