>and they would immediately be untrusted for doing so
Untrusted by whom? Let me remind you that Google also owns the most popular browser used to access the web. There are already plenty of websites that don't work in any other browser. So they won't even notice if non-Google browsers suddenly don't trust the certificate anymore.
I agree with your point, though you might be exaggerating their current market share a bit. But Chrome does not make certificate trust decisions on most platforms, so it would certainly be a wild scenario for them to do something like this.
Untrusted by whom? Let me remind you that Google also owns the most popular browser used to access the web. There are already plenty of websites that don't work in any other browser. So they won't even notice if non-Google browsers suddenly don't trust the certificate anymore.