Hi, new to AoS and the board 👋 Here are some of the ideas I'd like to see. Most aren't that original, but a couple might be out of left field hopefully:
Order:
Kurnothi and fairies
Stone/Crystal Duardin sworn to Valaya
Defenders of humanity (Order of Azyr, priests of Sigmar, Deathless Black Guard of Morr, that kind of stuff)
Chaos:
Chaos Dwarves
major skaven revamp
undivided Daemons to accompany Be'lakor, expanding on furies and such
Daemon princes for the major chaos gods - super-elite daemon prince/counts as troops?
Death:
cults of Nagash, accompanied by baba yaga-style hags, bog-mummies and hounds of the baskervilles
Automata - potentially following the brain-in-a-vat trope
Undead black ark malerion aelf liches leading drowned sailors and pirates in the vein of the flying dutchman crew in Pirates of the Carribean... or just simply vampirates ^^'
Destruction:
Insectoid Silent People
Dragonspawn leading an Apocalypse Cult. Also gelatinous cubes because why not
Knights following the aesthetics of the Old World White Wolves, sworn to revenge against Chaos and Sigmar. Humans potentially alongside Duardin?