I don't think 5 years is necessary. I think after two years of this agentic orchestration if you rarely touch code yourself skill will degrade to the point they won't be able to write anything non-trivial without assistance.
How much do you think Linus Torvalds has coded over the last decade? Why is he still able to do his job?
Depends how long you've done it, and how much the landscape has changed since then. I can still hop back into SQL and it all comes back to me though I haven't done it regularly at all for nearly 10 years.
In the web front-end world I'd be pretty much a newbie. I don't know any of the modern frameworks, everything I've used is legacy and obsolete today. I'd ramp up quicker than a new junior because I understand all the concepts of HTTP and how the web works, but I don't know any of the modern tooling.