the way I see it he left enough open questions or lets say "teasers" in the story unexplained to write another story that takes place in arelon.
We could read that the Pagan like rituals of the Fjordell people were also a way to gain access to the Dor. I think the whole concept of the Fjordell(ic)? Battlemonks and their way of Religion leaves alot room to play around. Sarene also mentioned some interesting fact about the first wyrn not beeing Derethic and I'm almost sure this can't be just a random unimportant fact Sanderson told us there. There is alot of ackground story to it.
Background story to Dreak the Iron (?)/ Kiin would be fun too.
How came it that the original religion got separeted into the three parts Shu-Korath,Shu-Dereth and (I forgot) .Also the Jeskeric Myths are a big point (which are basically downright satanistic rituals).
The Battledance Shuden practiced also seemed to be a way to access the Dor and it reminds strongly at real world Tai-chi which is said to is used to regulate the energy centers /chakras in your body.

I could imagine a big war between the other countries and Fjorden/fjordell? oh man I mix things up now. There also has to be other Countries too since the got named before so maybe they have their own ancient technices for the Dor.

Yes I wa quite impressed and I liked the Character Hrathen.

Mistborn Era 1


Mistborn Era 2

Stormlight Archive


Elantris

Warbreaker

Arcanum Unbound

Here are many of the covers of short stories/novella that are now in Arcanum Unbound



Also here is the art for The Reckoners series: