Thanks for that.
The wider ecological desolation and the resource scarcity for me are somewhat more attractive, but if you were to lean towards the anticapitalism I can see how the uprising of slaves against their masters may be the strong focus.
Having said that, there are many ways to tackle this - uprising against the masters, specialised unit to assassinate the sorcerer kings, pushback against the scarcity issue by reversing the ecological effects on the lands - thus breaking monopolies...etc
I recently ran an adventure in Ylari (Mystara) where the environment was the co-BBEG and our table seemed to enjoy it.
EDIT: When the monsters (Magmin) are rushing towards the party encampment but instead sidestep the characters and run with maniacal glee towards their backpacks with their precious waterskins, rations and equipment to set them ablaze that's when the players realised things were serious