Sure, maybe optimize further. Why have managers? The CD pipeline goes throughout the whole value stream, not just at delivery. Just like delivery automation (eliminate intervention of humans), there's also human automation (helping people get out of their own way). So I could see a use case where managers are just eliminated. You need people who can eliminate the noise and replace with enough signal that delivery teams can execute. POs and stakeholders can do that; managers not needed.

I think what you bring up though is an interesting point: maybe managers needs to transition to business engineering roles.

This all will play out in the 21st century. 20th century management is a legacy artifact at this point. Best example is F500s, which are generally mediocre in their execution. If a SpaceX type org (14k employees, private) gets into their space, they're screwed. Even with politicians in their pockets, I don't see how rock swallowing dinosaurs like Boeing (170k employees, public) will make it. Just the energy they have to expend to get anything done compared to SpaceX is massive, due in part to their giant management bureaucracy.