Normally, when a GPU developer creates a laptop SKU, they re-use the desktop branding, add an M at the end, but release a very different, significantly slower part. This changed with the GTX 980, as NVIDIA cherry-picked the heck out of their production to find chips that could operate full-speed at a lower-than-usual TDP. With less power (and cooling) to consider, they were sent to laptop manufacturers and integrated into high-end designs.
They still had the lower-performance 980M, though, which was confusing for potential customers. You needed to know to avoid the M, and trust the product page to correctly add the M as applicable. This is where PCGamer's scoop comes into play. Apparently, NVIDIA will stop “producing separate M versions of its desktop GPUs”. Also, they are expected to release their 10-series desktop GPUs to their laptop partners by late-summer.
Last time, NVIDIA took almost a year to bin enough GPUs for laptops. While we don't know how long they've been stockpiling GP104 GPUs, this, if the rumors are true, would just be about three months of lead-time for the desktop SKUs. Granted, Pascal is significantly more efficient than Maxwell. Maxwell tried to squeeze extra performance out of an existing fabrication node, while Pascal is a relatively smaller chip, benefiting from the industry's double-shrink in process technology. It's possible that they didn't need to drop the TDP threshold that far below what they accept for desktop.
For us desktop users, this also suggests that NVIDIA is not having too many issues with yield in general. I mean, if they were expecting GPU shortages to persist for months, you wouldn't expect that they would cut their supply further with a new product segment, particularly one that should require both decent volume and well-binned chips. This, again, might mean that we'll see desktop GPUs restock soon. Either that, or NVIDIA significantly miscalculated demand for new GPUs, and they needed to fulfill partner obligations that they made before reality struck.
Call it wishful thinking, but I don't think it's the latter.