Managers are the parasitic class, so they will take the company down with them, and will never be replaced. One can however start a new firm without them and without AI. All you need is to measure commits and communications to know if someone is working and how they should be organized. It doesn't even require AI.
Who measures them and how do they judge quality?
User activity and commit activity matter. If there is no user telemetry, something is not right. If users are filing too many bugs, something is very wrong. If users are filing feature requests, that's a good sign.