The hardest part will be keeping up with the rapid clip of today's web without the backing of an open source community writing extensions in JS itself. Supporting the babels, TypeScripts, and Flows of the world as they pop up with only an in-house team will be difficult.
How can you have a chance against WebStorm by not being the biggest editor?
WebStorm is IntelliJ Idea. It’s a full IDE with capabilities beyond that of a simple code editor: code analysis (for multiple languages), smart refactoring (for multiple languages), extensive plugin support, an extensive range of support for anything from eslint configs to understanding things like “oh, it’s an Angular app, let me help you connect all the pieces together”, etc. etc.
