Microsoft have already started doing this to developers (forced data-mining, a.k.a. telemetry) in .NET Core and VS Code - and to everyone in Windows 10 - so I don't see why they wouldn't do the same with Github.

...or else what? Are the developers going to mass-migrate to SourceForge?[1] Github has a lot of leeway/social capital - they are hardcoded into the infrastructure both literally and figuratively.

edit: 1. I literally forgot about Gitlab as a Github substitute when I wrote the comment, interpret that as you may.

> ...or else what? Are the developers going to mass-migrate

Yes, that is the obvious risk. Gitlab is the #2 in the space, right now they don't have much market share but if an avaricious corporation violated the spirit of Github? It might be the chance they need.

Bitbucket, gitlab, some other new service that takes advantage of the gap left by mismanagement?

I remembered Gitlab after I posted but before I saw your comment and made an edit. Github has network effects and inertia on its side - switching to any other service has a cost, and Microsoft has to piss off developers enough to justify the switch - moderate annoyances will be tolerated.