Adding languages by community, is it a good idea?
Honestly,I love Duolingo, but I don't like this new direction. I have got a feeling that the staff of Duolingo will get extremely busy with separating good pieces of information from bad and becoming a peace-maker in several discussions. In addition, adding and editing a lot languages a that same time could shut down servers.
The reason why the team decided not to add any more languages in their usual way is that this does not scale. They'll have to expand the staff constantly to add new languages, apparently, this is not what they want.
I think we'll wait and see what happens with the new way of adding languages. Crowdsourcing when cleverly managed can be a very powerful tool. There are quite a few people who help others to learn their native language for free. Most likely, there will be such people for other languages, too. They will help to create useful content and filter out mistakes. Then, the intermediate and advanced learners can help improve basic lessons.
I have a little bit more faith myself - the basic skill tree idea is developed enough that probably even I could could copy it, if I had any other languages to share. It also works plenty well enough for Memrise, and even though that is sometimes a bit sloppy, its nothing if not diverse: http://www.memrise.com/courses/english/native-american/
The idea of democratising the lessons is also nice in itself, because if for example someone random user thinks of a phrase that could far better illustrate a point, there is nothing stopping them from adding it.
It only really requires two things to work: a firm but fair (ie: not overbearing) level of 'curation' by someone on staff, and a cordial atmosphere between the users. I like to think we're all grown ups...
edit: whoops, meant to reply to original post, not reply to you, sorry.