Hello,
Similar to Sheetmetal workspace, we can have a Plastic Part design workspace and another submodule for Mold design either in the Plastic workspace or as a separate workspace. This will be helpful to design and build a plastic component from idea to actual product in Fusion 360 itself. Although Moldflow will be used for Flow analysis, if it's not too much to ask, Flow analysis tool similar to Inventor can be integrated into Fusion 360 for complete development.