Just curious, why would you need 16GB in the Macbook? Because i love my Macbook, but it ain't the memory that's holding back anything, it's the "slow" cpu mostly
That question could be perhaps answered by the fact that I upgraded my Hackintosh from 32GB to 64GB last Christmas
I use applications that eat a lot of RAM, such as virtual machines and radiosity rendering (yes, the matrix radiosity from the good old days, that needed a lot of space for caching form factors between patches), together with symbolic math analysis with Mathematica, which will eat all RAM you have, no matter how much.
I'm not sure if the substitute for my MacBook Air will be a MacBook or a MacBook Pro. My MBA is a late 2010 model, which I managed to keep at optimal CPU speed all these years, by not upgrading OS X (it's still at 10.6.8, it's a Core 2 Duo, and it boots OS X in a few seconds because it's at 10.6.8, it would take a lot longer to boot if I had updated OS X).
The Core 2 Duo is of course slower than the 4GHz i7 6700K I've in the Hackintosh from which I'm typing this, but however, it's still "fast enough" for a lot stuff I do in my MBA (yes, even Mathematica stuff, and VirtualBox machines). The most limiting factor in my MBA isn't the CPU, but its 4GB RAM (and its 256GB SSD, which is now at only 40GB free).
In a laptop I value lightness, because I tend to bring it with me in trips... I work with it in trains, buses, hotels... and the current MacBook (not the Pro) is even lighter than my MBA while providing more than 2x CPU performance compared to the Core 2 Duo.
If the MacBook gets updated to Kaby Lake and with a 16GB RAM option, it would very likely be my natural update path. It would mean scaling my MBA CPU speed by more than x2, as well as the RAM amount by x4, and the SSD by x2 or more.
Of course, the MacBook Pro would provide more performance, but whenever I try to configure a MacBook Pro at the Apple Store, I get a result which weighs more than the 1.30 kg of my MBA.
The only thing I don't like in the (non-Pro) MacBook is the graphics: integrated Intel graphics are getting more and more efficient, but my MBA had the integrated NVIDIA 320M, and I prefer to have an NVIDIA on board rather than Intel, but anyway, I guess I'll have to give up in that point.