By the sounds of it, you could do this currently.
1) Create a root image for your use that installs Salt in your Arch image. See here: https://github.com/pauldotknopf/darch-recipes/blob/master/ba...
2) For the rest of your recipes/layers, create a script/bash file like you would normally, but just pass execution to Salt.
I'll look into Salt more. Maybe there is a way to extend Darch to support different "executors" to support things like bash/Salt/Puppet/etc.
All you have to do is install Salt, and then you can run salt-call to apply states.
Yes, Salt states can depend on other states, and you could choose to apply only selected states.