I don't think so. Theymos stated that he don't want to destroy the marketing industry in the forum (signature campaigns, in particular); but he will probably think about this 'last' (might be last) solution if the merit system failed to control / eliminate spammers out of the forum. I strongly believe that Theymos will not launch new rules which prohibit signature campaigns, because as you can see merit system has shown strong positive impacts on the forum users (on different ranks of users, from lower-ranked to higher-ranked users).