Stalker has read of many transformations of mushroom units into different enterprises, most legal, some illegal.
Usually the change is into something else vaguely horticultural. There was the farm in England that was used to illegally store tyres though.
Now in Canada comes a quite startling morph, from horticulture to aquaculture. The project is to transform a former mushroom substrate composting facility in Thames Centre, Middlesex County.
Fish food for thought for any entrepreneurial soul thinking of switching out of compost production and into a more fishy business.