Firefox works on Wayland now. So, unless you have redefined Firefox as a non-major browser, "is far from certain whether any of the major browsers will ever run on Wayland" is flatly wrong. Also: https://github.com/01org/ozone-wayland

And the obvious point is that turning ChromeOS into a full linux distribution defeats the point of ChromeOS itself: to have very few "moving parts", and only those necessary to launch Chrome. Also, the bulk of the work "for wayland" is not wayland itself: it is KMS/Mesa/glamor/libinput, which are already used by ChromeOS (except for libinput, I think).