In terms of the actual social network... people use that sh? I've had my moments of Facebook addiction in the distant past, but there's nothing about LinkedIn that makes me look forward to logging in. My feed is mostly composed of inspirational quotes, people celebrating their anniversary at their current job, corporate brown-nosing, articles on productivity, articles about people quitting their job, etc. All generic, mostly low-effort junk. Let's not even get started on the recruiter spam!
Unfortunately, it we will have to wait for a serious decline of LinkedIn before a serious competitor can make headway.