Developers are really particular about their setup, and choosing an editor is one of the most personal decisions a developer makes. Languages change, jobs change, you often get a new computer or upgrade your OS, but you usually pick an editor and grow with it for years. The last thing I would want to do is take that decision away from Atom users.
Atom is a fantastic editor with a healthy community, adoring fans, excellent design, and a promising foray into real-time collaboration. At Microsoft, we already use every editor from Atom to VS Code to Sublime to Vim, and we want developers to use any editor they prefer with GitHub.
So we will continue to develop and support both Atom and VS Code going forward.
Obviously, trusting Microsoft is how you get left in the desert staked out over an anthill without your editor of choice, but it's a little better to at least hear the new puppet CEO of Github commit to it.