All of that is going to need cooling. I don't see this and the cooling solution fitting into a "NUC" form factor case. It'll likely be some variation of mini-ITX.
That doesn't make sense - if this was a test board and not a prototype/pre-production of a planned product, it wouldn't be that densely packed. If you're just validating parts, there's no reason to spend time and money engineering a dense board like this - and this board is clearly not as large as a mini-ITX motherboard. Not to mention that for it to be ITX, it would need a 24-pin ATX power connector, 4- or 8-pin EPS power, and it would likely include some sort of PCIe slot. It could be adapted into thin ITX (which can run on external power), but I don't see how that would make sense with this TDP.
Dunno... maybe a big blower will get the job done.
If it is indeed the future ZBox Magnus, the PC case is going to be tall enough for a decent 95W low-profile heatsink.
Yep. Microsoft cools the APU+VRAM+VRM for the Xbox One X (which runs around 150-160W under gaming loads (170-180W at the wall) with a large blower fan (~100mm) and a mid-sized aluminium fin stack on a vapor chamber. Judging from reviews, it does so very, very quietly to boot. For this, they could just stick on a mid-sized purpose-built heatsink with some heatpipes, with a 120mm fan blowing down - and the whole thing would be cooled relatively efficiently. It wouldn't be thin, though.
You might be right. Still think it would need about 5-6mm more space in the z-axis at minimum.
There's little reason to suspect this will be low-profile like the mainstream NUCs. Zotac and Gigabyte doesn't have the Z-height aversion that Intel seems to have, illustrated by the vertical RAM slots on this board. You couldn't cool a 100W heat source in one of the smallest NUC sizes without duct taping a Delta fan to it anyhow.
