As great as the Eames Lounge Chair is, I think it looks like it was created in the 1950s. A better example of a timeless piece of design would be the Barcelona Chair, which predates even the Eames Chair. It still looks modern, nearly a century after it was created.
Add Le Corbusier's LC2 (to the eames and barcelona chair) and and you have a few timeless designs, all from mid-century.
http://ecx.images-amazon.com/images/I/41a30HNuKeL.jpg
To the people discounting timeless design: yes most of contemporary industrial design is disposable, but some pieces from Braun and Apple will be considered classics.
"And it never will"
I would never pay for a Picasso or a Van Gogh to hang in my house (because it's would be exorbitant and) because it doesn't evoke positive emotions when I look at it. Norman Rockwell does just that and he has since I was a kid, does that make his art better than Picasso's? Not to most people.
Just because ideas about how a chair can be designed remain popular doesn't mean that it stops being subjective.
The Eames Lounge Chair was designed in 1956. At no point since then has it looked dated. And it never will. It's timeless (and comfortable as well). http://www.hermanmiller.com/products/seating/lounge-seating/...
Its difficult to make timeless work with software because the capabilities and mediums change so rapidly. But we'll get there eventually.