Someone needs to reimplement a "clean" version of its functionality: professional networking is too important to be left to the data hoarders/government surveillance cluster of organizations.
Besides, its UX has decayed to a "Facebook for the employed", where John Doe praises himself for mastering a mandatory training at work or taking Introduction to HTML at "Harvard" via Coursera.
Nobody is coming to save us. A federated LinkedIn would be great but will not take over. We just need to stop using these services
The problem is a competitor will never be able to succeed without doing the same thing. Try to compete as a "free" service and you'll have to sell ads, try to charge and you'll never get enough signups to fund the business.