Very impressive! Those maps are stellar, the concepts and well over all this is a very interesting take of what could be lurking below the snow.
The idea of visiting darker places of Azeroth, especially ones brimming with the creepy crawly and ancient elritch tentacled things! As fascinated me since Arthas' stumble with an Old one..back in WC3. Now with the Mogu and Titans lore from 5.2. This perks up the concept of what secrets the Titan's have been hiding...
Plus there is no doubt a subterranean beauty to it all. Like glittering reaches of Deepholm, and the Azjol-Nerub dungeons themselves have glowing fungi and gilded architecture to silk webbing platforms in various rich colors .Such as decor like that of amberweb pass in Blood Myst...
While we did get a lot of about the Twilight's Hammer and Old God things in Cata -> Dragon Soul's it was rather let down...
at any rate I wonder if you ever considered making a mod as a proof for concept, while sadly there is no public World builder for WoW. Closet bet would be SC2's Galaxy Editor... or roll old school with WC3 mapping tool?
While custom models and actual game play stuff would be a challenge.. I could see some of your dungeon ideas being able to be created and experienced to some degree.
Last but not least, ever wonder what happened to these Woolly Scorpion mobs in WC3...the arachnathids?