Finally, the look and feel and comfort of devices is critical to their market acceptance and usefulness in practical situations. Handheld devices continue to get thinner and more lightweight. That's awesome, provided they continue to be important for AR.

Most of us agree that eventually all of this will move into wearable eyewear. Unless you're in an industrial hardhat environment, we all look forward to the day when AR eyewear becomes as lightweight and comfortable as a pair of sunglasses. Then, we'll wish for AR contact lenses (then, retinal implants?).

In 2009, Rolf Hainich described the ultimate display in his book The End of Hardware: Augmented Reality and Beyond as follows: