URGH. Terrible news.
(The TL;DR on my view is that the “Open Web” advocates look at walled gardens from a browser perspective but not from a services perspective. Once Chrome can be required on iOS, Google will likely do it for its services. Combine it with the removal of ad blockers coming up, this can destroy browser diversity for good. OWA assumes browsers are on equal footing, but people prefer service access to browser choice, they will switch in a heartbeat.)