VideoCardz reached out to Yuri and got to hear that this information was obtained by analyzing AMD's AGESA 1.0.8.1. Zen 3 based parts with 10 cores are supported by this AGESA version, so it seems that AMD is at least testing this configuration internally.
Next, Yuri notes that Zen 3 processors will feature a Curve Optimizer. This feature will allow frequency adjustment on a per-core basis without limitations.
Another new feature is Infinity Fabric dividers, Yuri expects this will "get the memory controller frequency slightly higher in mixed mode."
AMD's Ryzen 4000 series is expected later this year.