> it cannot understand your company’s history, constraints, and business logic like an experienced engineer can

Not yet, but those are management skills.

What stops seniors being replaced by managers weilding AI, is that all the AI are still equivalent to only one pair of eyes.

Reason: whatever the AI fails at, whatever mistake it makes, it will have a really hard time catching itself and correcting. This remains true even when it is better than any single human developer, which it isn't yet, but then this does reduce the human role to QA and management of the AI.

Replacement depends on the complexity and size of the company. It will happen though as the AI improves. Even Meta is replacing senior engineers if they see their way to more profit without losing efficiency.