Perhaps the crux is: what is “value”?

If we mean dollar value then yes, hand crafted code may go to zero as nobody wants to pay a 10x premium for it.

If we mean (as I did) the subjective value to the creator themself, then there is no reason this has to stop. It will just make the same shift as farming to gardening.

You shouldn’t expect to get paid for this, or do it on your employer’s time, but you are absolutely free to do it in your leisure time, and perhaps just like Go and Chess, AI will make these pursuits more accessible than ever, to those who are interested in learning for fun.