Personally I believe that this must be some kind of engineering sample or otherwise. I refuse to believe that Intel would make so many obviously bad choices that would be picked up by every single reviewer, every gaming site and most technically minded users.
1. 16 PCIe rather than 20 (CPU lanes), unless the PCH makes up for these with additional lanes (which are inferior to direct CPU lanes), this simply makes no sense. Ideally you want the GPU and at least one NVMe SSD running directly to the CPU, with full x16 and x4 bandwidth.
2. A lower single core speed? There is no reason for this, in use cases that stress only one core, the other 5 don't matter as to overall power consumption, so staying within the 45w envelope is absolutely possible (as noted by the increase of single core to quad core clocks from 7th to 8th gen desktop CPUs across the board). It would be a blatantly obvious downgrade, for no real technical reason. Historically, single core turbos have improved *every* generation since the introduction of the Core i**** series. I find it very doubtful that Intel has reversed this for no apparent logical reason. Especially with the introduction of actual competition from AMD.
3. How can it be the same BGA socket? The six core requires different power delivery, hence the move from z270 to z370.
4. The most obvious route for Intel, compared to the 7700hq would be +100/200mhz on single core turbo clocks, +100 to dual core clocks, +100/no change mhz to quad core clocks, and -200/300mhz to six core clocks (comparatively from quad core limits).
These are made on the assumption that the 8700hq is a direct replacement for the 7700hq. If it's some kind of 8720hq, it may not be intended to be, and perhaps the 8700hq is instead a quad core with higher clocks, or is simply skipped this generation. It may be the case that high boost clocks+high core count is simply not possible with 14nm, regardless of how many +++ there are in the current generation.
Again, think about it from an overall perspective, what would Intel look like releasing a comparative downgrade in most use cases from their last gen CPUs, at the same time that Ryzen has been introduced?