If display ad revenue as a way of monetizing knowledge and expertise dries up, why would we assume that all of the same level of information will still be put out there for free on the public internet?

Paywalls on steroids for "vetted" content and an increasingly-hard-to-navigate mix of people sharing good info for free + spam and misinformation (now also machine generated!) to try to capture the last of the search traffic and display ad monetization market.