“we will begin testing a change where links clicked on within the Windows Mail app will open in Microsoft Edge”.
Are you using the Windows Mail app? It's Microsoft to Microsoft. They're not forcing Edge for everything. They're just locking down link handlers within their own application.
Of course, quite true, and as I noted above in #67, the headline is overstated.
OTOH, it's an indication that Microsoft is still Microsoft, and it's obviously and demonstrably to Microsoft's advantage to have complete control over the Win10 environment, top to bottom. "Windows As A Service" and "Win10 is the final 'version' of Windows, from now on it's just 'Windows'" indicate clearly that the days of an open platform for third parties are coming to a close. The rules have changed.
Only a fool would believe or argue that Microsoft does not want tight control over the Windows ecosystem.
Note that I don't condemn this. It's Microsoft's right to do so, and it's to their business and market advantage, long term, to do so. They're doing what they need to do.
The reason this little kerfluffle is interesting (other than the sensationalist/FUD aspects) is that it's a "feeler" about whether they can get away with locking things down again.
So first they mention it happening in an application almost nobody cares about. If nobody bitches, they'll be encouraged to try elsewhere. If there's a lot of pushback -- which could only be on principle, given the infinitesimal use of the Mail app -- they have tested the water in a safe way and can try something else.