It's too early to get a clear picture, but my thoughts so far:

If the merit system completely fails and I can't think of anything else to replace it, then my next step will probably be to completely remove all ways for forum users to make money from posting (eg. removing signatures entirely).

Maybe there are ways for people who were making money by posting garbage on the forum to make money on other sites with easy bounties, etc. (For example, I don't know if they're actually any good, but https://bountyhive.io is currently advertising on the forum.) But people should use the forum to talk about these money-making ideas, not as a way of making money itself. Once you spend a lot of time here, you may be able to make some money here (which is great!), but you should consider this a far-off hope, not your primary objective.

BTW, if anyone has any ideas for simple things that these ex-nonsense-posters could usefully do to make money, I think that this'd be a good project right now. There are apparently quite a few people who were making money on the forum and could use guidance. Even though their past activities were not good for this forum, I doubt that they are useless in general.