I did not look at it that way but after you pointed to how account farmers could indeed counter any possible positive effect the banning of mixers could have brought to the equation, it is something that could happen. If they do need to increase the number of posts using even more multiple accounts then it could add more spam and much more low quality posts to the forum. I do hope we will start seeing less spam/flooding but that could be wishful thinking.
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?
I am afraid it will lead to the opposite of what you say.
I have no study to prove this but here is what I think. More opportunities of earning a regular income means an user is more likely to work on a single Bitcoin Talk account to reach a well paid Signature Campaign and have a small posting quota. If they used to earn 150 a week with an account they will now need three accounts and triple the posts to earn the same money.
It means one of three things. They continue with one account and accept their fate, they give up or they create two more accounts so they can earn just as much again.
This will be an indirect incentive for more users to purchase and sell more accounts. Easier to try to abuse and get into Signature Campaigns quicker.
But then if they had to do 25 posts per week before, they need 75 with three accounts. Either they write 50 more brain farts or they still write less farts but never get to the max quota.