This functionality is implemented in ArcGIS Pro.
Note that since these are parallel edit sessions on different workspaces when it comes time to save one save may succeed while another fails. If it is important that the edits be guaranteed to be made together keeping the data in the same workspace is the solution.
There are also issues with having versioned and non-versioned data in the same geodatabase. As these are the same workspace with different session lifetimes due to the varying support for undo/redo. Things can get a little complicated. For example if you have outstanding edits against a versioned FC you won't be able to make edits to non-versioned FCs in that same workspace until you save your edits while you can continue to make edits to non-versioned FCs in a different workspace without saving your edits (but those edits of course will be immediately committed without undo/redo/discard capabilities).
Retrieving data ...