No, they are removing the ability to create them. The existing contributions will remain.
Not quite. It seems like creators have until September 28 to choose to publish existing community contributions, and if they don't, it seems like they will all disappear. That's how I interpret, "You have until September 28, 2020 to publish your community contributions before they’re removed."
If you have contributions currently saved as drafts, these will be available for the next 60 days (until Sept 28 2020), and you have until then to publish them before they’re removed. Any already published contributions (titles, descriptions, captions, etc) will continue to show up on videos and can be managed by Creators in YouTube Studio.