Epyc 4 is Genoa. Frontier will use special chip rumored to have 15 chiplets, with GPU chiplets added to the CPU and I/O dies. This can then be sold to the general market as well. AMD is advancing rapidly with their architecture!
Rumors are starting to appear on Navi and Ryzen 3. More info will be released by E3, and certainly by 7/7/19 launch date.