It would seem that https://github.com/atom/atom-languageclient is still under active development. Hopefully this means that the core Atom team will continue to work on language server features.
A fairly substantial PR was accepted recently to integrate the typescript server as the language client for atom-ide: https://github.com/atom/ide-typescript
It appears the project isn't dead, but there aren't any Facebook maintainers working on it (and there haven't been for nearly a year).
It appears the project isn't dead, but there aren't any Facebook maintainers working on it (and there haven't been for nearly a year).