Honestly not super sure if that is more of a risk than it was pre-llm.
As part of the aquisition I got access to their previous codebase which was some sort of incomprehensible PHP monolith, with the persons who wrote that code long gone. Thanks to LLMs I was actually able to extract the core useful concepts (again, sufficiently deep domain knowledge that I knew exactly what to look for). Without LLMs i would have probably extracted the absolute minimum and let the rest rot.
There is no reason a dev of comparable skill and domain knowledge would not be able to do that for what I built here.
But that codebase was written by people, so you'd be well positioned to take it over. I wonder if the same would be the case if you were to take over a codebase that was written by AI.
By that point it might no longer matter though, but I suspect that such code would have a lot more exposed edge cases than one where someone actually thought things through before coding.