An interesting observation was made by Guru3D editor and developer Yuri Bubliy, on his twitter account, he posted something interesting, 1usmusmentions Zen3 with 10 cores are a real option. 

In Agesa version 1.0.8.1 support for processors (with ten cores) based on the Zen 3 architecture would be found. Ryzen 4000 based on Zen3 is expected to launch late this year. It would be interesting to see if it's a proc as the current design holds 8-cores per-die. In theory, it would be possible to have two CCDs with 5-cores, but everything in technology land always mathematically correct and din pairs and 5 sounds very odd. There's alway the option for more dies though.

Yury found more, a feature called "Curve Optimizer," will be introduced. This allows a more efficient boost algorithm, and hear me out now, that's per-core. The first processors with Zen 3 cores will be released at the end of this year. Processors without integrated GPU are codenamed, Vermeer. Whether AMD will actually release Ryzen 4000 processors with ten cores is unknown.

Yuri Bubliy is currently developing ClockTuner for Ryzen, a semi-automated application for retrieving the best performance out of CCX in Ryzen processors.

Zen 3 processors with ten cores coming up?