I'm not talking about facebook. I've implemented this for Fortune 50 financial firms and telcos. Wall Street Journal is react. Wal-Mart is all in on react and even open sourced their own isomorphic framework. It's being adopted very broadly and very quickly.
I haven't seen such a quick uptake in enterprise, since the late 90s when everyone began using Java and universities took it up as a teaching language.
Enterprise cares predominantly about hireability, and Javascript has been the only language for the web for decades. Everyone who even tangentially has a brush with web technologies knows it, and if your company has a frontend team you already have people at your company who know Javascript well.
I predict Javascript will continue to see growing use serverside, at least until the point ten years from now when WebAssembly is mature enough that people can develop for the frontend as well as the backend in any language.