Earlier quoted context omitted.
It would be interesting if Google tweaked their Chromium licensing so that Edge couldn't use it. Then Microsoft wouldn't have a browser at all.
Microsoft could just keep an independent fork—just match features at a slower pace. Google can't change the license of Blink, their renderer, since it's a fork of KDE's LGPL renderer.
edit: but honestly, Google could go Apple open source way, making code changes in huge dumps that are impossible to integrate back. But I an not sure it’s worth the trouble.