I don't think they'll end up doing that for the same reason that Google didn't put the Dart VM in Chrome. Nobody wants to be the one to start the nuclear war.
Google has done this before. When they blocked Hangouts in non-Chrome browsers, spoofing your User Agent would allow it to load and, probably predictably since I'm making this comment, Hangouts worked absolutely fine in Firefox. Not sure if it still works these days, but I don't use Hangouts anymore.
There's also the whole Shadow DOM v0 stuff with YouTube that more or less artificially slows down rendering in non-Chrome browsers.
I have never had this problem with Hangouts in Firefox. Hangouts has a million bugs on its own, but it works similarly poorly in Chrome and Firefox and has for a long time as far as I can tell.
