In reply to Tim Kaye.

Gutenberg is absolutely being designed to let plugins work together seamlessly. The issue you're linking to is regarding backwards-compatibility with existing plugins that manipulate content. In this case, Gutenberg needs to provide a common API for plugins to interact with the blocks. It's the exact same thing for PWA features: core needs to provide a common API for plugins seamlessly to extend the web app manifest and the service worker. In the case of the PWA plugin, however, there isn't really a concern for backwards-compatibility since it is a new technology.