Rigid rear axles are quite common on 4x4 type vehicles and also on light (and heavy) commercials, especially in developing countries. Morgan axles, as far as I am aware, are made in Australia by a factory owned by Dana - a large US parts supplier. They incidentally also now own the factory in Birmingham where the GKN axles were made. They also have plants in USA, Mexico, Brazil, you name it.
These axles are relatively easy to adapt to different customer requirements - the lengths of the axle arms and half shafts are simple to make to the required size to get the track you want. Spring brackets and other bits and pieces can be welded on as needed.
Rigid axles will be around for a long time yet!
