> Within a very short period of time all code will be AI code.

This is unlikely. Perhaps “most code”, but not “all”.

People can overwhelmingly shift to a new technology, but the old one usually remains in use, even if niche.

Yeah there are still people out there hand-crafting Assembly. Not so sure about punch carding though; maybe some extreme retro getup.

Once most code is AI slop, then the training data is tainted -- you know what happens when you eat your own crap ...