$SUBJ. Bad thoughs after this article.
Atom is open-source so Atom would continue if github died which is extremely unlikely.
I undestand the problem and I don’t thin Atom will die anytime soon (or nothing at all). Although I’m worried a lot with the current development cycle of Atom and priority of bugs, and specially the way that APIs are changing, I don’t think Atom will stop being developed.
Yet, if for some reason it dies, probably I’ll migrate to LightTable. I’m working on it right now, in Clojure Development, and it’s quite stable and have some very interesting ideas.