New Language Suggestion
I think Duolingo should have Sanskrit because it's kind of a dying language and it has a deep and rich history to it. If you could consider it that would be cool!
If you considering to add Sanskrit language, then you should also add Lithuanian language as this langues is the oldest alive language. Lithuanian language has relations with Sanskrit language and having in mind the significant geographic distance between India and Lithuania this similarity is a mystery. http://vilnews.com/2011-04-incredible-indian-lithuanian-relations-2 Lithuanian language is mother tongue language for around only 3 million people.