While that's still true for iPad, it certainly is not true for iPod touches or iPhones. My 2nd gen iPod touch is stuck at iOS 3.3 with its completely different version of Safari.

And it's 2 years old.

So you're technically correct that Apple has not yet obsoleted the device they released one year ago. Given their track record though, I don't think I'd put too much faith in that continuing to be the case.