Stormwind and Orgrimmar 9.2.5 Updates - What Are The New Stables and Workers in Capital Cities For?

wowhead.com:

With patch 9.2.5 on the PTR, dataminers and testers have noticed some changes that have been made to old zones in Azeroth. For example, Steve Danuser has already confirmed that the datamined changes to the map of Tirisfal Glades has to do with story involving Calia Menethil, the Forsaken, and others. One particularly mysterious change has been the addition of stables in Orgrimmar and Stormwind City — along with workers who seem to be building something else.

New stables have been added to the Mage Quarter in Stormwind and the Valley of Strength in Orgrimmar. The reason for their addition is not yet clear. PTR Stormwind Stable PTR Orgrimmar Stable Same Areas on Live Servers for Stormwind and Orgrimmar

The stables aren't the only mysterious additions to these areas. Each also has a wagonloads of goods nearby, filled with decorative odds and ends.

Finally, each area also includes a new NPC offering a short questline each — questlines that involve rounding up workers and setting them to work building… something. The Story of 9.2.5 — Workers in Capital Cities It's clear something is going on, but exactly what remains unclear. As the questgivers themselves say,

While we certainly can't tell without more details, we can speculate on the meaning of these additions to the Capital Cities. Since we are getting shiny new dragon mounts in Dragonflight, it could be tempting to think these stables are specially designed to house these mounts. However, that makes little sense — since it's been stated that dragonriding system will only be available on the Dragon Isles themselves. Besides, they don't really scream «suitable