Personally, I think there's a few things theymos should do rather than nothing.
1) Offer or auction some long term deals to companies that are already trusted and have a history of advertising here. Many of these gambling companies are sponsoring streamers millions a month so I'm sure they'd put up a fairly large amount for a years ad subscription or something.
2) Hire someone trusted to vet all new adverts.
3 Implement Silver/Gold/Platinum/Lamborghini Memberships like the current Copper one that come with the benefits of a Full/Senior/Hero/Legendary etc, and maybe even some additional perks with a higher "premium" rank like the ability to change name, access to a exclusive sub board and so on.
Being able to purchase these memberships have numerous benefits:
Completely passive income for the forum
Essentially stops account sales and farming
Will severely dent people from fishing/begging for merit
Fantastic, bitcointalk is one the richest forum in the world with almost 25 Million USD funds. the forum shared $7 each.
Whilst the forum does have a lot of money held in reserves it will only dwindle over time, and there's always the risk of bitcoin having a massive crash. We've already seen it lose well over half its value since the all time high. I'm sure we will see much more volatility over the next ten years with even worse crashes along the way.