Thank you for the interesting read. Having said that, I would have tackled this topic from a different angle… Relevance. A relevant design would stay timeless. A relevant design makes it iconic. Let me explain.
Car enthusiasts are still drawn towards the design of 911 the same way they did 50+ years ago. The whole selling point of 911 being a “pure bred sport car that you can drive everyday” remains relevant all these year. That’s why it’s timeles and iconic. To expand on this, the friendly-priced original Mini can also stay relevant being a “small, light, kart-like handling trill ride”, and therefore the design is timeless and iconic. The same theory applies to wrist watches from Patek to Seiko.
So for digital design to become timeless, we should be aiming for it to remain relevant. And at this point, the example that you’ve brought up (Google Home Page) has remain relevant among all the internet users. If you ask me, I would have categorize it as iconic already. Whether it will be timeless remains to be seen. But looking at the simple, purpose oriented, no compromise approach to this Google design, it has all the potential to become a timeless search engine desgin as well.