1.2.5 has been pushed, with the ability to provide multiple families to instances, and specifically for Maya, more solid menu item and icons.
instance.data["families"] = ["geometry", "human", "primary"]
This would typically be utilised in your Collector, to expose a particular Instance to available plug-ins. For example, you may install a series of plug-ins from an external source, such as Pyblish Magenta, and register interest in some of it's plug-ins, such as it's ability to export alembic files, or Pyblish FTrack and register interest in having an instance be registered with FTrack.
In short, it's a brave new world!