The SoC die is bigger than the one used for the GTX 1080 + 12GB of GDDR5 + all the other components for a SFF computer.
Breaking even at $399 seems like a stretch.
If it ran standard Windows it would be a steal at $499 IMO.
You also have to factor in Microsoft Messaging on the this. When ever asked about pricing Microsoft repeats two things:
It's Premium, or it's High End.
That implies definitely higher than $399 pricing.
It will be more than that, and lots of people will whine, and lots of people will buy one so they can have the "best" console.
All this, huge SOC, 12GB GDDR5, beefier GPU than an RX480, 1TB HDD, and a UHD Blu-Ray player...
$ 599 all day with the specs theyre throwing around.
You guys saying 299 and 399 are delusional