If GitHub now supports "unlimited" "free" "private" repos, how will they generate revenue? Does this mean advertising will be an issue with GitHub?

It's not unlimited, you can have only 3 collaborators on a free private repo.

Most businesses will pay to remove this limitation.

Also, free private repos boost Github's acquisition, those who were previously put in bitbucket/gitlab because they offered free private repos.

It's a clever move from their part IMO.

And it gives Microsoft access to a ton of developers to whom it wants to push its own tools/ecosphere (which it is already doing very successfully).

Not to mention, it’s quite possible they (and their developers) were already spending quite a bit of money on repos annually themselves.

THEY DO? That is awesome. I think.