1) Are there any news in the open source Firmware front?
I'm not of the "open source everything" crowd as I am aware that there are things that involves the Intellectual Property of several companies, so any such effort would fall into a lawyer's maze. However, AMD could still provide the require binary blobs and documentation to initialize the Hardware. If my memory serves me correctly, last time I checked, Coreboot seems to not support Zen because AMD didn't provided the bare minimum to do so, and reverse engineering would take ages.
2) Will there be SoC-style Zen based products for entry level consumer?
As much as I love Zen itself, a thing that annoys me to no end is that there are no Motherboards that I know of that uses Zen as a pure SoC. AMD announced the A300 and X300 Chipsets back when Ryzen was launched, intended for mITX Motherboards, but I think that no one did products with them.
The thing is, Ryzens using Socket AM4 have 24 PCIe Lanes available (4 are used by the Chipset), while the Zen die itself has 32 and I think that the recently announced EPYC Embedded products can actually use all of them. Zen also has embedded USB3, SATA Controller and even a hidden 10 GBit NIC. A mATX sized embedded Ryzen or Raven Ridge would need no Chipset at all, it should be rather cheap and great for some minimalist builds (Even including Internet Cafes), and still pack a punch.
A full Chipset adds Motherboard complexity, power consumption, latency and cost, and all of them are stupid considering that in entry level builds Zen itself as a SoC could happily carry the entire build. It really gets me on my nerves that Zen is such a great piece of silicon and most Motherboards manufacturers doesn't realize its potential.
And that leads me to...
3) Will AMD try at some point vertical integration of the product stack, like designing reference Motherboards but for production instead of internal testing?
The best way to solve points 1 and 2, would be that AMD tried designing a few reference Motherboards and make them available for the typical Motherboards partners to manufacture and support, as to not compete with them. This would be similar to what happens with Video Cards, so I don't see that it is an impossible idea.
If AMD designed a Motherboard from the ground up, it could pick the other components of the platform based on the availability of end user documentation. This way, instead of providing just some code to initialize the Hardware then leaving the Coreboot community the task of having to reverse engineer one by one a few Motherboards to implement whatever support chips they use (And most never get to the fully feature complete stage), you could have a Motherboard that from the ground up is intended to cater to that audience, so everything about it is functional and documented.
I think that an embedded Raven Ridge in mATX Form Factor with open source Firmware would be a one-of-a-kind platform. Simple, cheap, auditable, somewhat expandable...