I'm hoping they would also offer Dothraki.
Dothraki was also created by conlanguer David J. Peterson, and the best thing, is that Mr. Peterson created the Duolingo HV along with some of his students. But, He wants to create a 2.0 tree, because he thinks that the course is too short, and we'll have to wait until that happens to finally have Dothraki in the incubator.
My understanding was that he sold certain intellectual rights relating to Dothraki to Living Language, which company understandably will not, so far as its rights extend (which it apparently considers to be quite a long way), consent to allowing a free course on DL that would rival its own proprietary course. Unless this legal situation changes, I don't foresee there ever being a Dothraki course on DL.
if you want to contribute to a course, the Dothraki flag is on the list and I think allowed to be created.