Eurocom is quite liberal when sharing confidential information in support forums. It was one of the first sources that predicted that Intel would develop the Z390 Express chipset and also say that Intel is preparing to increase kernels on its MSDT (desktop) platform once again, in 2019.
Apparently, the chipset of the 300 series, led by the Z390 Express, will support the silicon "Ice Lake" of 9th generation and 10 nanometers of Intel with 8 physical cores.
The generational successor of the i7-8700K will be, therefore, an 8-core / 16-wire chip. This also presents Intel with the opportunity to make its next Core i5 pieces of 8 cores / 8 threads or 6 cores / 12 threads, and Core i3 of 6 cores / 6 threads or 4 cores / 8 threads.