At this point, they won't release any mobile GPU until next year, we soon in summer, there is few announcement but a doubt
for a release of new mobile GPU in time for this year.
To be honest most game don't even use 50% of the modern mobile GPU, most of the game are ported from weak hardware (console) that are well defined
hardware so benefit a lot from optimization, you will be able to run all the actual games and next 2 to 3 years game without problem on
actual mobile GPU and even previous one.
And with the arrival of external GPU capability using usb-c, to be honest, it is a better solution for future gaming or heavy task usage.
First revision of Pascal GPU won't be more powerful than Maxwell one due to similar component arch usage, Pascal first model will be
a Maxwell 16mm with new features/more cuda core but nothing interesting yet, expect no more than 15% performance
it will be good for energy usage but in terms of performance it would be a little bit better.
Since they release the GTX 980 (not M) for Laptop, again I doubt you will see a pascal based GPU for this year on laptop, they
can announce but won't be available before Q1 2017, so you have time and again it won't change that much, you
you can buy a maxwell based laptop now is enoug + external GPU later (XG2 is coming) 😉