"It seems to me that a lot of you "bring on our new overlords" boosters are unaware of how HTML5 came about. It was not through one vendor shipping proprietary code and standards bodies mopping up later. Study some recent history."
V8 folks promise to work with TC39 on semantics and open source the code, which helps. You're right that, worst case, this turns into another Chrome-only power play. But all signs suggest otherwise, so far.
https://brendaneich.com/2007/11/my-media-ajax-keynote/
/be