This model seems to be a derivative of the Zen server parts, it's described as a multi-chip module (MCM) with two Ryzen 7 dies in a single package. Canard PC claims samples are going around and that they do 2.4GHz/2.8GHz, that they have a TDP of around 150W and support quad-channel DDR4 memory. Presumably, this platform could also offer more PCIe lanes than what's supported by the X370 chipset.
The Ryzen parts for the HEDT market will not be compatible with current motherboards, it's a separate platform just like Intel's Broadwell-E. CanardPC claims these parts will use Socket LGA SP3r2 and will require a motherboard with the X399 chipset (which seems like a weird name for an AMD chipset). We haven't heard about SP3r2 before but we do know the upcoming Naples server part uses the SP3 LGA socket.
I would take the rumor with a grain of salt but CanardPC claims we can expect an announcement or a launch in 4 to 6 months.
Il y a bien des Ryzen 16C/32T axés HEDT prévus sur X399 dans 4/6 mois. Clocks ~2.4/2.8G. 2 dies MCM. 4 chan DDR4. Socket LGA SP3r2. ~150W. ????— Canard PC Hardware (@CPCHardware) 18 maart 2017
CanardPC also claims AMD could attempt to make a 4-die MCM part that offers eight-channel DDR4 memory support, with clockspeeds over 3GHz and a massive 200W TDP.
Les clocks / TDP sont issus des samples actuels. AMD peut toujours tenter un CPU @ 3+GHz à 200+W au final (voir à 4d MCM pour 8ch DDR4)... ????— Canard PC Hardware (@CPCHardware) 18 maart 2017