This why it's very difficult to imagine that an iPad five or 10 years from now will look, feel, or even function very differently from the ones we have right now. It's also why all the tablets of Apple's competitors at CES feel even more irrelevant than ever. Once you perfect the design of a window down to its essence, the only thing that matters about it anymore is the vista it overlooks.
I respectively disagree. Right now, the iPad is a solved design problem. In the context of today's technology, today's tastes and today's expectations, the iPad (both mini and Air) are almost perfectly designed.
But technology, tastes and expectations change. What we want today is different than what we wanted five years ago. Did we ever want an iPad five years ago? I hardly think we realized there was room for a tablet in the computing world.
Four years after the introduction of the iPad, we can't imagine life without it. Who is to say we can't imagine a bezel-less iPad four years down the road?
Design, like a want, is subjective. Perfect design concepts change from era to era.
There is always room for design iteration. Just give it a few years.