On the Firefox side, we are considering supporting the protocol or a subset of it. It seems many people have had lots of trouble with WebDriver/Selenium in the past and are hesitant to use it. However, it is nice that WebDriver has a W3C standard which could provide a nice path forward for headless cross browser use. This would probably require browser vendors to make it a first class citizen and work out some the kinks of the spec though.
BTW, I'm in Mozilla San Francisco office, so I'd be happy to chat about the headless cross browser future if anyone from the headless Chrome team is around.
BTW, I'm in Mozilla San Francisco office, so I'd be happy to chat about the headless cross browser future if anyone from the headless Chrome team is around.