Matrix is an open, federated protocol so something like this can't happen. Worst that could happen is bad stuff happens to Element (the flagship client) at which point people can either fork it or simply use another client.
That could be true but the track record hasn’t been good and it definitely won’t happen without a concerted effort to support it.
I am absolutely in favor of open protocols, but they are not a guarantee against needing to change ecosystems in the future.