You could forget maybe how a certain lib or framework worked or things like that, or more so how you wouldn't have been up to date with all the new ones, but ultimately code can be represented as just functions with input and output, and that's all there is to it.
As in how could I possibly forget what loops, conditionals or functions are?
I haven't written code myself for 1+ year (because AI does it), but I feel like I have forgot absolutely nothing, in fact I feel like I have learned more about coding, because I see what patterns AI uses vs what I did or people did, and I am able to witness different patterns either work out or not work out much faster in front of my eyes.
Now writing is something totally different. In some cases writing ability is not about writing, it's about your thoughts and understanding of life and human nature.
You could simply become a better writer without not writing anything by just observing.
If you are using an LLM to write, what is the purpose of that? Are you writing news articles or are you writing a story reflecting your observations of human nature with novel insights? In the latter case you couldn't utilize AI in the first place as you'd have to convey what you are trying to say within your own words, as AI would just "average" your prompt or meaning, which takes away from the initial point.
With code it's desired that it's to be expected, with good writing it's supposed to be something that is unexpectedly insightful. It's completely different.
To become a better X to must do more of X. There are few shortcuts worthwhile.
Although we were discussing about the decay of skill in something. While in some things the decay is super clear (as in running - pace, not the technique), I think there's many areas where there's no clear decay and other activities will actually significantly boost it, and any decay that there is, will be removed in just few days of practice or remembering.
There's many more ways to evaluate a writer skill in terms of what they are doing vs what is coding. Coding can be creative, but in most cases you are not evaluating coding as writing, unless it's possibly technical writing, which is still different compared to coding.
So you may remember all your high school math, but not doing it every day, means you are slower than some of the students. So your knowledge of programming will be there, bit you will be slower because you no longer have the reflex that comes with doing things over and over.
There's also plenty of things that I have got for life just by having practiced them when I was child. E.g. I think everyone gets bicycling, but there's also handstand, walking on hands, etc, which I learned as a kid for few years, and I can still do it even if I only do it once a year. In my view code is exactly the same, and maybe in a way even more straightforward, it's easier than obscure math since you don't have to memorize any formulas to solve it easily, albeit I think a lot of math is great because you don't have to memorize formulas in the first place you just have to internalize or figure out the logic or the idea behind it, and then you just have it. I think repetition in math is specifically the wrong way to go about it, it's about understanding, not repetition.
But if I didn't need those things, and there was a simple pseudolang syntax which acted exactly the same in all versions, didn't have any breaking changes, I would argue I'd be much better at it now.
Internet, search etc is needed to understand how to setup libs/frameworks/APIs, but logic at itself isn't something that I could possibly forget. AI will help to get those setups quicker without me having to search, but arguably it's all useless information, that will get out of date, that I really don't even need to know. I don't need to know top of my head what the perfect modern tsconfig setup should look like or what is the best monorepo framework and how to set it up, so it would scalably support all different coding languages for different purposes.