It seems NVIDIA is planning to launch GeForce GTX 1070 and GTX 1080 cards for laptops, just like it did with its GeForce GTX 980. There will reportedly be no special M versions for the high-end laptop segment, these will be the same chips used for desktops, with the same number of shader units and the same clockspeeds. They will operate at a lower TDP though.
MXM specifications are rather strict in TDP limits. If AMD or NVIDIA were to follow these regulations, their graphics would be limited to 100W (MXM 3.0 type B). By introducing custom boards, MXM regulations are no longer a concern. However those cards need to be adopted by notebook manufacturers, and of course that’s not cheap.
PCGamer report is lacking in details, but we can suspect that NVIDIA will only use Pascal GP104 for those non-M series. Other GPUs like GP106 were already seen in MXM 3.0 format, so I suppose those are going to continue using the M-branding.