Well I am still in the loop as a senior dev and I get to review everyones code before it gets merged. Official guidelines is that everybody is responsible for the code they produce (with or without AI) and must understand it when they give it to the reviewer. I've been doiing this 3+ years at this company, so before the whole AI thing landed. I am explicitly not allowed to implement features myself (because the idea is the juniors learn and get trained).

Now, within the last 6-12 months of AI advancement, I think you could lay off half or even 3/4 of the team if I was explicitly allowed to implement features myself using AI. But that is not the current policy.

As for worries "ending up on a codebase you can't manage without AI" - my personal take is: No, I am not worried. Because going forward AI will always be available in the development workflow. That is my own opinion, not the corporation standpoint, however.