In the forum as far as a huge number of farmed-accounts and alt-accounts are concerned, will the lack of opportunities to earn a regular income equate to less spam, less flooding and less merit abuse? The only to know definitively is to allow time but if the spammers leave the forum they will not be missed and that cannot be a bad thing.
Thinking to all the mixer related campaigns we had, majority of the ones I remember were managed expertly and did not encourage spam at all. Many of the users on those campaigns will also be welcome into existing campaigns or have been already.
What action will have a significant effect on spam will be stopping bounty campaigns and signature campaigns altogether.