Any plans for a Sankey chart? I'd eventually also expect related charts such as Parallel Sets and Flow Maps? I was a bit surprised to not see any requests for this chart type yet. If this chart type is considered, adding support for a vertical orientation (horizontal is traditional) would really open things up.
Here are some Sankey references:
https://en.wikipedia.org/wiki/Sankey_diagram
http://www.sankey-diagrams.com/