GitLab CI/CD for GitHub

Hello,

According to https://about.gitlab.com/solutions/github/, from sep 22 2019, this feature will be moved from free subscriptions to silver subscriptions. However, I’m not completely sure what exactly will change? Right now we have some repositories which are mirrored from GitHub and which runs CI. Will this functionality stop working?

Does this also mean that completely mirroring repositories will be non-free?