Ok, this is coming from a guy that hasn't yet dug deep into the lore of the world. However, i think i have gathered enough info to conclude that the dwarves dissaperance is a mystery.
Thus, this gives all the freedom to their creaters to do as they pleased with the dwarves. So, for some DLC i would like to see a long quest line on figuring out what planet the dwarves ended up on. Getting a space craft operating again to visit that planet and reintroduce the existence of dwarves back into the tamerial universe. I mean we have every dam race imagionable but dwarves, and quite frankly, i would like to see them again.
Granted, it would be better agrued that the dwarves somehow dissaperaed deep into the earth rather than going into outspace but i think the quest to build a new space ship and solve a mystery as why they left the planet to being with, would make more sense and be more interesting than figuring out how and why they simply decieded to lives as pure moles. Furthermore, going to space would seem more consisent with the context we find the dwarves to be in within tamerial.
I mean they arugably had a more advance world then even our own real world. All it would take for humanity to go back to the stone age would be an emp blast in a certain area. Thus, upon visiting this new world were the dwarves found a new home it could be an anything goes enviorment. It could break all the rules as to what we consider the norm for the EOS universe, which would mean there would have to be certain boundaries that couldn't be crossed.
Anyway, that's my jab at it, i doubt that under tough scurtiny it could with stand the brains of the EOS scholars, but who knows, i just thought it would be a sick ass dlc and a brilliant way to explain and reintroduce the dwarves.
cheers.