The Coffee Lake-S CPUs are slated to be released in late September this year. The initial models will be compatible with Socket 1151 motherboards and they will integrate 4 cores or 6 cores. The Cannon Lake CPUs coming early 2018 will also require the new Z370 and an unannounced "300 Series" chipset that features HTPC additions.
https://www.notebookcheck.net/Leaked-slides-reveal-more-Coffee-Lake-CPU-details.240424.0.html