I am curious as to any new languages that may start appearing in the incubator. Arabic? Mandarin? Afrikaans?
Since the courses are built by the users, the sky is the limit! I would start a betting pool, since it would be super exciting, but Duolingo would not much appreciate that. My bets are Arabic, Urdu, and Persian! The major European languages(and a lot of minor ones) are already almost all up there.