Duo, is there anything in the pipeline to offer more choices so that we can actually spend our lingots? (I am getting close to 7000 at this point....) I would love to see more units added to the tree to give one example of something that could be done!
There is a new format coming out see here: https://www.duolingo.com/comment/25615588/Upcoming-Feature-Skill-Levels It is more advanced than the present format.
But no lingots required. I have a lot of lingots also and I use them to send encouragement to good comments and my streak freeze. Let's see what the future brings.