Unfortunately not in the way it works currently.
This is however a question I have seen many times so I guess we really need to consider bringing the functionality back in some way if possible.
The way I see it it had two major use cases:
- Show the legend embedded in the map: This I think can be solved in some way with the new dockable windows. You can create a docked legend that might not exactly be embedded in the map, but at least it can be shown next to the map window.
- Print the legend embedded in the map: This can now be done by positioning the legend window in a frame on top of the map in a layout window.
Would this solve the use cases you are seeing/having?