The potential designs are posted on Mozilla’s Open Design blog for anyone to comment on. A final direction will be chosen by the end of September 2016.
From the blog: “We’re updating our brand identity using Mozilla open source principles, and everyone’s invited. In this, our [c]oncepting phase, we’re narrowing from seven possible themes to a few concepts that will proceed to iterative design work. Your comments on the work in progress are welcome.”
Full explanations with plenty of accompanying visuals and comment space can be found here.