FWIW I've run into a lot of regulatory people who have pretty clear views that Bitcoin mining should be regulated such that addresses are blacklisted or even whitelisted. Obviously that's a goal, not necessarily what they'll succeed in making happen, but that's what the long-term intent is. For instance, one regulator I talked to a few months ago at a conference was *very* clear in her view that the Bitcoin protocol simply must be changed to add verified digital identities to the protocol itself, and mining blocks with transactions without valid identities and/or extending blockchains with non-compliant transactions should be an illegal activity that's prosecuted.