That is a very unlikely edge case. If it were to happen, Servo is an open-source project, and would likely still see development.

> What if Microsoft doesn't ever get a significant number of users on Edge?

That is somewhat more likely, but as much as I can hope, probably will not happen. At least Edge renders fairly correctly.

> like Windows Phone.

Windows Phone simply failed to get inertia. Inertia is imperative for proprietary projects to succeed.