It would be nice if these diagrams could be used for multiple varibles.
Also, it would be cool if the you could color all flows based on the color of one of the variables from which they flow like you can do in the case of the alluvial package in R. Check this example with the Titanic Survivors dataset -> https://github.com/mbojan/alluvial
I find this is the most important feature of the alluvial package that was not implemented in any python package that implements Sankey Diagrams like Plotly. This feature would be very useful for viasualy analyzing categorical variables.