Do you think asking any LLM in the next 100 years to "write a Python script that generates an OS" will work?
It'll fail miserably at making it human-friendly though, and attempt to pilfer existing popular designs. If it builds a GUI, it's be a horrible mashup of Windows 7/8/10/11, various versions of OSX / MacOS, iOS, and Android. It won't 'get' the difference between desktop, laptop, mobile, or tablet. It might apply HIG rules, but that would end up with a clone at best.
In short, it would most likely make something technically passable but nightmareish to use.
Given a century the only unreasonable part is oneshotting with no details, context, or follow up questions. If you tell Linus Torvalds "write a python script that generates and OS", his response won't be the script, it'll be "who are you and how did you get into my house".
If you're expecting OSX, AI will certainly be able to make that and better "in the next 100 years". Though perhaps not oneshotting off something as vague as "make an OS" without followup questions about target architecture and desired features.