>if this cuts the knees out from under the competition

All of Github's competitors (i.e. gitlab and bitbucket) already offer unlimited private repos. This is Github catching up.

Exactly,while it is dramatic for github, it has to do this because of competitions.

As well as MS’s own Azure Devops aka VSTS as well as free hosted builder servers, private package repos, project management, etc. for up to five users.

I was thinking that Bitbucket still has its promise to always be free.

However, I don't think it will be an issue. As hosting costs drop to zero, if someone starts charging, they lose customers to a free competitor. (as is happening here).

But that is a non-sensical argument unless you are saying that making all those accounts free will somehow reduce the overhead related to the personal accounts. Seems like it will in fact increase costs as more people sign up.