Stop dreaming about a 16". Kill the 13" and put all the energy into a thin and sexy 14". I edit my photos on the go on a 12" MacBook. If you are serious about photography, get a $1500 100% AdobeRGB and hook it up to your Macbook. Remember it is a laptop, and not a dinosaur called 'desktop replacement'. The amount of size queens on this site urging the return of a 17" is too damn high.
The 13" Air & Pro models are by far the most popular notebooks that Apple sell, so the 13" isn't going anywhere. The 2016 Pro models will remain the same screen sizes (a source last week incorrectly claimed Apple are working on slimmer new 13" & 15" MacBook Air's, they are in fact Pro's).
The amount of people urging for the return of the 17" is too damn high? What does that tell you? It means there's a market for this model! The only reason Apple scrapped the 17" Pro was because there wasn't a viable 'Retina' screen available. The cost of producing such a screen was and still is astronomical.