Here's what durable means from a dictionary -> "Able to withstand wear, pressure, or damage; hard-wearing."
Not one laptop (well, those Toughbooks) seem to withstand wear or pressure so right out of the gate your "spec" removed all 600ish dollar ultrabooks.
As to future proof, what if folk skip Windows 8 and MSFT rolls out 9 in one year? Will you claim your ultrabook was not futureproof because you can't install that?
I'm looking for a good future-proof and durable laptop that is easy to carry around. The 14" models seem to be a good idea since I don't need something large, and can hook it up to an external monitor for use at home. My budget is $600 max, but would prefer it to cost less than that. Durability is a big factor in my decision, as well of upgrading possibilities without voiding the warranty.
There's a number of them in the price range, but like I said there is either no reviews, or they aren't very good.