It appears Siege of Orgrimmar will be added as a Timewalking raid in Patch 10.1.7.
This week’s Patch 10.1.7 build adds copies of items from the Siege of Orgrimmar loot table. This can only mean Blizzard intends to add a new raid to go with Mists of Pandaria Timewalking.
We won’t go over every single one, but you get the idea! Looking forward to Siege of Orgrimmar Timewalking?