I think the stacker news model is working and a stackoverflow type of site would work perfectly with the same model. And then the viablilty of micropayments as a business model is a question of scale. In this model, any kind of engagement beyond just reading costs some sats. On the other hand, overly paywalled sites seem to languish for lack of engagement. Imho, even the people who don't boost/tip are providing the value of of their eyeballs, which incentives those that do engage.