Initially announced to be a Kirin 980 device, the Mate X, which got delayed once again, is said to be getting an upgrade to the unannounced Kirin 990 SoC. Besides a new ARM Cortex-A77 core cluster, the new SoC will also integrate a 5G modem and will enable 4K@60 fps recording capabilities, and, to take advantage of the increased resolution Huawei is also throwing in a P30 camera setup.
https://www.notebookcheck.net/Delayed-Huawei-Mate-X-primed-for-Kirin-990-SoC-upgrade-and-P30-camera-setup.431136.0.html