This idea builds on the new "memory workspace" output option for geoprocessing tools added in 3.5. The context is when a layer is saved to memory workspace and added to a map, then ArcGIS Pro - and the map - are closed and re-opened. The layer would be automatically removed from the map and a message would pop up notifying the user "the following memory workspace layers have been automatically removed from the map:" followed by a list of the layers that were removed and an option to add them back to the map as broken layers.
This may help reinforce to new users what the memory workspace option does. It may also help save users time searching for a data source for a broken layer that doesn't exist because they forgot they saved it to memory.
Currently, the layer remains in the Contents pane as a broken layer with no notification.
