It’s a play for dev mindshare where they get to control the platform and have access to devs using their software, they have no intentions of making money from it directly only to maximize its appeal & marketshare. It’s a cross-platform dev environment they can easily deliver extensions to connect to their commercial products.

There’s no point in them continuing to invest in fragmenting the dev community by developing 2 competing platforms now that they own GitHub so I’m not expecting to see any increased investments in Atom.