What is the next big display tech apple will use?

In 2001 Apple released the original iPod with a black and white screen. Eventually they released the iPod photo with a small color display. Then the iPod video. Eventually they released the iPhone, and the iPad. The retina iPhone and the retina iPad. There is no denying that Apple has been very forward thinking when it comes to display technology, as this is the main way we interact with our devices. When apple released the iPhone 4, most of us were blown away. We didn't the it was possible to have such a high PPI at the time.

Assuming this trend continues of exponential increases in screen size, quality, and pixel density, when will we look back in the current iPhone/iPad retina displays and think "I can't believe how crummy the displays used to be!" What technology will cause us to think this way? Is there something out there that most people are not aware of?