You're right! I think NVIDIA might release it in 2016.
This is based on some of the articles I've read. The Pascal GPU's will definitely be faster, lighter, and more power efficient (similiar to NVIDIA's past GPU upgrades). However, I'm unsure of the cost of the potentially updated Y50.
It shouldn't vary too much from the current cost of a Y50, but definitely if there was a price change, it'd be the higher end of 200-300 more. Since the Pascal GPU's may be released in 2016, I can see Lenovo updating their Y-Series line with new Intel Processors and this year's, 800M series GPU's. Since it's just a processor upgrade, I can't see the price changing too significantly for 2015.
You can refer to this for a history of Y-Series releases for Lenovo to predict a possible release - (http
/en.wikipedia.org/wiki/IdeaPad_Y_Series#Y500)