So, first off, take all this with a giant grain of salt. It's a dealer, so if you believe nothing a dealer says, which is a good idea, then don't read this. But it's a small data point, so I'm going to leave it here.
Just got off the phone with my dealer. He was just seeing if he could drum up a bit of business as my lease is up in 6 months. He wanted to know what my plans were. I said I was waiting to see what was happening with the '16: if Nissan increases the range, I'll buy that new. Otherwise, I'm going to buy another used '13. He said he was pretty sure the '16 was going to have 150 miles. I asked him if he meant the '17, and he said no, he had heard the '16.
So, couple things to keep in mind. First off, not much for him to gain by making something up: if the '16 comes out with 80 miles, he didn't get a sale by making **** up today. Second is that he was the one who said 150 miles, so he at least knows what the current rumors are. And third is that this is a dealer which does a pretty good Leaf business. A good quarter of their lot at any one time is dedicated to Leafs.
Of course, he could just browse this forum every once in a while and that's where he got his information. So, eh. But 150 miles next year would be nice!