If you pay attention to the culture of photography, you'll have noticed the sustained, steep decline in sales/usage of digital point-and-shoot cameras. Flickr's Camera Finder reveals that the top 5 cameras for its users over the past year are found in smartphones, not stand-alone devices. The top 3 are various iPhones stretching back to the 4S. Apple didn't just disrupt the mobile phone market; they made waves in the camera industry as well.
The quality of Apple's iPhone cameras seems to come from three major pieces: great physical components (many of which are custom), powerful image processing chips, and excellent software to make the most of the previous two. But the iPhone 6 highlighted some limitations: the camera can only shrink so much while maintaining image quality, so we get a wart on the back of a device that's too thin to accommodate the camera and all its pieces. Physics wins again.
We've seen Apple address challenges like this in other areas, however. They developed a new method for milling aluminum for their device cases. Apple even claims to have created a new alloy of 18k gold with increased hardness for their new watch. I'm sure that Apple (and every other device maker with half a brain) is throwing a lot of hardware engineers at battery technology, but my great hope is that we hear about some breakthrough in optical engineering out of Cupertino in the next few years. I don't see a lot of incentive for Nikon or Canon to figure out how to cram a higher quality camera into a shallower depth. Couple Apple's recent work in materials science with their excellent software and we may be a few short years away from something truly incredible.
At least I'm hopin'.