It may become possible to do a census-like approach. @ned has spoken about a unique identity database, maintained by oracles (they may be Steem witnesses or witnesses for an SMT). With that, there will be a split between accounts that are verified unique persons (VUP?) and those that aren't (non-VUP).

We could maintain a similar database for non-VUP's that are identified as bots. All of this could be done on the Steem blockchain, but would be a significant development effort.