A 10-core 20-thread Intel Cascade Lake-X CPU belonging to the Glacier Falls platform has surfaced on UserBench. Not much information is gained from the listing itself, but we do see the CPU being listed with low base and boost clocks.
https://www.notebookcheck.net/10C-20T-Intel-Cascade-Lake-X-Glacier-Falls-HEDT-processor-shows-up-on-UserBench.428114.0.html
Gigabyte already showcased "X299G" motherboards (G just means it's a newer mobo) that are LGA 2066, not LGA 3647. It will just have 18 cores max and not 24 as there are no changes to the mesh layout.