The fact that Blink is open source is totally irrelevant; sure it may mean that some niche browsers can exist with a few tweaks, but any serious attempt at fork

The fact that Blink is open source is totally irrelevant; sure it may mean that some niche browsers can exist with a few tweaks, but any serious attempt at forking would require a legion of developers. If Microsoft isn't able to maintain their own browser, the idea that some other org out there is going to have the resources to fork it is laughable.