I think you are confusing manager with ICs. Managers don't really read or review the codes. What you are describing is where agents are doing all the coding and reviewing without people in the loop. I don't think the op is working with the code as black box. He is more about describing the higher IC workflow.
Whether we still need people in the coding loop is not a trivial difference
Good ones do. Reading the code someone is contributing is a powerful signal about how well they're doing.
ICs who manage swarms of agents should operate the same way. They set them off to do something, and then look at the output to see if it's going well.
That's the point I'm making here: managing a team of ICs and managing a swarm of agents has a lot of overlap in the systems and processes you can use to see if it's working well. By teaching ICs to be better managers I think they'd get better at using agentic AI.
There's such and such. In some companies, the leaf engineers report to a team lead, which might or might not be granted this 'manager' title. Those poor fellows essentially doing double-duty and are the most likely candidates for burn-out.
Whether we still need people in the coding loop is not a trivial difference