The official Gigabyte AORUS Twitter published a 10 second long teaser video advertising a new motherboard. The implication seems to be that the Z390 chipset (and perhaps 9th generation Intel CPUs) are coming in early October.
https://www.notebookcheck.net/Gigabyte-AORUS-teases-new-motherboard-for-October-8-Z390-launch-in-October.333078.0.html