I don’t think 4chan is next. I believe the site has staying power because its users are anonymous. Anonymity means it’s very difficult for leaders to emerge which means it’s difficult to rally behind a particular cause. This means it’s difficult for 4chan to grow in influence as an organized force. It’s just a steady state of low-level chaos, which is good for containment. I’m also quite confident that the FBI monitors the site and I don’t think they want to see all those borderline people scurry off into different corners of the internet should the site go offline.