I don't know for sure what the 2016s will bring but the 2015 coaches are pretty amazing and if what you see is what you like I'd go with what is right in front of you. Plus, you'll save any price increases that the 2016s will bring.
You might kick yourself later if the 2016s turn out to be better but if you just concentrate on enjoying your 2015 and don't worry about the 2016s you'll be happy. Of course if you do wait and buy a 2016, then you'll probably kick yourself later when the 2017s come out. That's a never ending cycle that you can never win.
Your other alternative is to wait and see what the 2016s look like. But if you don't like them as much as the 2015s, then it'll most likely be too late to find a 2015 in dealer stock with the right options, color and interior that you want. Then you may have to order a 2016, wait for it to be built, and pay the increase in price.
It's a tough call but buying an RV is always full of decisions to make.