They said the same thing about their cloud streaming service, so it would seem Game Pass will evolve to offer streaming and/or download options depending on the device.
Regarding the other platforms, I think Spencer mentioned in another interview that they'll focus on PC and Android first. As for other consoles, I could see Nintendo eventually going for it but not Sony.
And I don't think this means MS is leaving hardware. Spencer already said he doesn't seen streaming replacing consoles and they want to offer the best hardware on which to play games, so it only makes sense to see xCloud and Game Pass on every platform as their way of expanding the business.