The text of the Systems Specifications for Shadowlands was updated a few minutes ago on our Support Site: https://us.battle.net/support/en/article/256565
The minimum requirements section for Storage now reads:
Solid State Drive (SSD)
100GB available space
Or
Hard Disk Drive (HDD)
100GB available space (depending on the performance of the drive, player experience may be impacted on HDD)
Please note: the System Requirements for this game may change over time.