Anyway, my point is that centralisation isn't bad if it's painless to decentralise again.

I'd love to see GitHub (and GitLab) offer a custom domain name option which would proxy HTTPS and SSH clones via a company's custom domain (e.g. code.example.com) to GitHub's hosting. That way, if a company needs to move away from GitHub (or GitHub goes away), developer's references to some company's code is not stuck pointing to some stale github.com domain.

Hosting such a proxy (and the repos) takes infrastructure, time, and experience to secure and make available, so from a user's perspective it's great if a company does this as a service as long as you provide the domain.