I'm going to give a very boring answer with regards to monetization strategy: they should sell licenses to Dwarf Fortress, or Dwarf Fortress Supporter Edition, which is distinguished from DF Vanilla by saying that it's the supporter edition and maybe some cosmetic change somewhere.
I would price it at $19, where it would be towards the top-end of indie games on Steam; by the standards of people who enjoy Dwarf Fortress, Dwarf Fortress ROFLstomps the depth and quality of any other $19 entertainment option.
I would then immediately solicit inclusion in a Humble Bundle, in the expectation that Humble Bundle would leap at the chance. One could envision a rougelike or Df-alike bundle; I anticipate that Humble Bundle would give DF top billing in whatever deal was negotiated. I would model that Humble Bundle as doing > $800k in sales, of which DF's take would be > ~$80k. Throw in "and we'll use Humble as our exclusive e-commerce provider for 12 months" since I think it is fairly clear that the authors don't want to be in the e-commerce business; that gives Humble ~10% of their gross revenue for next year.
Stage 3 of the master plan: get the game onto Steam. This might require $X,000 worth of production-ready art and video assets to satisfy Steam's requirements; $X,000 will not be a material amount of money to Dwarf Fortress, LLC.
The above unsolicited opinions are coming from a place of love for small software businesses generally and Dwarf Fortress in particular. Strike the earth.