At least that's my take on it. One of the key arguments for Facebook to persuade publishers into Instant Articles is that they load ast, offer a slick user experience, simplay work brilliantly - while most mobile publisher pages would not be optimized for Facebook browser, work slowly, etc.
So Google helps publishers in its DNI initiative with a huge open source project. When they launched the initiative, my interpretation already was that this was aimed to defend against Facebook (http://epapa100.blogspot.de/2015/05/my-take-on-googles-new-publisher.html), but now with the headline "Instant. Everywhere." it should become very clear where they are heading.