12C is made from 6C chiplets which are broken 8C chiplets. 6C chiplets are essentially a waste product. 16C needs to be made of TWO healthy chiplets and no 16C CPU yet supports my theory that AMD has chiplet shortage possibly due to using them in server CPUs. 8C made of ONE healthy chiplets are announced, but nobody yet knows the real availability of processors after launch. There may be not so many of them available.
This isn't AMD coming out with an X2 and X3 product after a while because the chips would be trash otherwise. These are useful chips through their entire product line and AMD's entire development and profitability relies on them making good use of these chips. It's not a coincidence that the 3900x is 2x the price of the 3600x and only $100 more than 2 much lower performance 3600. 3600,3600x, at least 1 TR3, 2-4 EPYC CPU's will all use this chip.
8C probably has the highest demand in the EPYC lineup as purchase to price ratio flips for data centers. But other things play part in this. Even though the 3600's, 3700x, and 3800x are using in demand chiplets on top of the 3900x it's entirely possible that AMD needs to sell these at a certain price to make them a viable profit center compared to EPYC. AMD tends to sell their CPU's as of lately at a certain price per core on current models all the way up the lineup (including EPYC within reason). We all suspect that the Zen2 will be a datacenter game changer. Assuming that's the case ASP on Ryzen affects AMD's allotment of dies. If they drove down Ryzen prices and too negatively affected their margins, then they would shift more of their dies to EPYC.
The good news is AMD's capabilities is even more fluid then if has ever been before. Which means they can react quicker to shifts in market. Including competition from Intel. I wouldn't assume the introductory prices will hold out for the long run. But there is just soooooo much more in play then just the cost of Ryzen 3k and its profitability. It helps on top of that, that its closest competitor in performance is $700 more expensive. If this was AMD of the Athlon64 days, this would be a 1k Product, just because Intel's is at 1.2k