The graph is scary, but I think it's conflating two things: 1. Newbies asking badly written basic questions, barely allowed to stay, and answered by hungry users trying to farm points, never to be re-read again. This used to be the vast majority of SO questions by number. 2. Experiencied users facing a novel problem, asking questions that will be the primary search result for years to come. It's #1 that's being canib…
If SO manages to stay online, it'll still be there for #2 people to present their problems. Don't underestimate the number of bored people still scouring the site for puzzles to solve.
SE Inc, the company, are trying all kinds of things to revitalize the site, in the service of ad revenue. They even introduced types of questions that are entirely exempt from moderation. Those posts feel literally like reddit or any other forum. Threaded discussions, no negative scores, ...
If SE Inc decides to call it quits and shut the place down and freeze it into a dataset, or sell it to some SEO company, that would be a loss.