The site says Intel will show the X299 and besides the Core i7-7740K we can also expect the somewhat cheaper Core i5-7640K.
Both models are quad-core chips based on the 14nm Kaby Lake-X architecture. Specifications-wise, the 7640K is believed to be relatively similar to the i5-7600K, while the 7740K is expected to be a slightly faster version of the Core i7-7700K. Both models use the LGA2066 socket and require a motherboard with the X299 chipset.
Both chips are pretty weird ducks and based on what we know today it's hard to see why people would shelve out extra money for these parts. Unlike the higher-end Skylake-X, Kaby Lake-X is limited to dual-channel memory and you're also stuck with the same number of PCIe lanes as the regular Kaby Lake-S.