I frequently need to compare two or more landcover data sets to show change over time. Nothing does this quite so well as a Sankey diagram, not that I have ever been able to create one. It would be a great charting enhancement.
It does not only work well for comparing landcover, but there are a host of other applications for it across multiple disciplines (financial, socioeconomic, engineering, etc).
Pro has a fantastic set of charting functions and i am hoping that this can also be implemented.