At this point, nothing will. I still see people come up with arguments that myspace was in a similar situation,but FB is nothing like MySpace. Users have spent more than 10 years sharing things, sticking to them and there's no way to step them from it. But what other companies can do is to try create services which helps certain kinds of people. Like people typically use FB for news, friend's know how, photos, random viral videos and if a company can take off users from FB by creating a better way to read news or share pics, there might stand a chance.

The way to unseat an established network is to build a network no one controls, which makes it the obvious alternative for anyone dissatisfied with the monopolist. Decentralization yields powerful network effects, and we're all about to watch it unfold. If you want to be a part of it, dive into the decentralized application communities that are forming around Ethereum and IPFS.