A reference to an unnamed Intel 8-core CPU has popped up in the 3DMark database and while the information at hand is scarce, all indications point to it being a 'Coffee Lake-S' chip. As per earlier leaked roadmaps, the new 8-core CPU should also see the arrival of the Z390-chipset and both the new CPU and Z390 boards can be expected to launch sometime in H2 2018.
https://www.notebookcheck.net/Unnamed-8-core-Intel-Coffee-Lake-S-spotted-in-3DMark-database-Z390-chipset-on-the-anvil.290262.0.html