GTX 1080 already available on notebooks. GTX 980M is no longer the best gaming laptop.

Nvidia is readying the release of the new 10-series chips for laptop. They won't design M versions of desktop GPUs. They will used the same chips as be used on the desktops, just operating at a lower TDP—we're told there will be the same number of shader units, etc.
We're also told that Nvidia will not go back to producing separate M versions of its desktop GPUs, which is good news for those looking for better gaming performance on the road or in a desktop replacement type notebook. Traditionally, GeForce M version GPUs were cut down quite a bit compared to their desktop counterparts (e.g. 970M is 1280 cores @ ~993MHz and 970 is 1664 cores @ ~1178MHz).

We can see the new notebook aimed GeForce GTX 1080 and GeForce GTX 1070 graphics cards around August / September which indicates a third quarter launch. This isn’t the first time NVIDIA is going to release mobile parts that achieve performance parity with desktop parts. Last year, NVIDIA announced a high end GeForce GTX 980 graphics card solution for mobile platforms which had the same GPU specifications along with higher VRAM and toned down clock speeds achieving better performance than the desktop variant.