Reputation systems are nice for providing a carnal motivation, but moderation is likely going to be necessary to maintain a high quality density. Crowd-sourced moderation a la slashdot is a reasonable place to start. I think there's a lot of room for improvement in this space, though. An academic publishing

I hope that in the future, something like ArXiv with a discussion system will be built on a fully distributed network a la IPFS. That's been one of my most ambitious dream projects since my third year of grad school. I haven't made any progress towards it. I think such a system could stave off some of the decline in academia. I'm glad that ArXiv is headed in that direction. They're the experts.