https://wccftech.com/wow-shadowlands-ssd-pre-patch-9-0-1/

WoW Shadowlands Requires an SSD to Play, Blizzard Says; Shadowlands Pre-Patch 9.0.1 Expected To Release Between September 22 and 29

The system requirements for the upcoming World of Warcraft Shadowlands expansion have been updated, and according to Blizzard, an SSD drive is required to play the expansion.