In my experience it doesn't really work that way. It's somewhat akin to a house that's undergone multiple remodels. You eventually run out of the house's structural capacity for more remodeling and you have to start gutting the interior, reframing, etc. to reset the clock.

At least today the coding agents will cheat, choose the wrong pattern, brute force a solution where an abstraction or extra system was needed, etc. A few PR's won't make this a problem, but after not very long at all in a repo that a dev team is constantly contributing to (via their herds of agents) it can get pretty gnarly, and suddenly it looks like the agents are struggling with tech debt.

Maybe one day we can stop writing programming languages. It's a thought-provoking idea, but in practice I don't think we're there yet.