As I've said in the main review thread, AMD's GCN 2.0 needs to be very efficient or they are dead.
Efficiency is king in notebooks & mobiles, and that's a huge market they cannot afford to constantly lose.
In the short-term, their only option is to price-cut and that will hurt their profits. AMD needs their GPU division to make the money, because their R&D for CPUs & APUs are funded by the only profitable division: Graphics.
AMD have already lost the war against Nvidia in the gaming mobile space.
GTX 780M have been the best mobile gaming card since May 2013. AMD still haven`t responded.
Now Maxwell GTX 970M and GTX 980M is out on notebooks in October, beating a GTX 780M by 70-80%. Probably 2x as fast as R9 M290X.
Alienware, MSI, Asus and Gigabyte which are big brands for notebooks are only offering Nvidia GPUs for the gaming notebooks.
AMD can release a huge and hot chip for desktop, but that isnt something they can shove in a notebook due to thermal restriction. So unless AMD have a new architecture, Nvidia will continue alone on that market.
That we have seen no leaks regarding new architecture from AMD, that they made a huge event just for Tonga which should have never existed. I dont know, but it seems dark regarding that they have an answer to Maxwell.
HBM is one thing, but bandwidth alone is nothing without the cores to push things through that wide road