I'd be in favor of a ban that would basically turn high-rank offenders into newbies (take away merits, signature, etc) but let them keep their account and continue on the forum. Most would disappear anyway, since they're here for money only. This has been proposed is some shape or form multiple times but I wouldn't hold my breath. For now the only path is to get theymos' personal attention with a "good for the forum" appeal and get the permaban downgraded to temp+sig ban.
Given that we know sig bans can be given out and are able to be mass-distributed (e.g. YoBit) I would be interested in seeing the effects of turning permbans into 1 month user ban + 1 year (or more) signature bans. This bottlenecks sig spammers as they are cut from the main incentive but provides an opportunity for genuine users to return after a cooling period. (They still deserve a punishment)