This makes me wonder what role fire normally plays in the life-cycle of tree pathogens. Does this fungus survive heat well? Can it survive in the soil long enough to spread to a new host (presumably a new Oak tree)?

As a second point, this demonstrates the danger presented by monoculture. The industrialization of agriculture horticulture has been unquestionably beneficial for us as a species. However, we do an absolutely terrible job of managing existential risks in horticulture. When we grow crops, we grow millions of acres of the same crop. When we plant trees, we plant thousands of the same trees. City streets in the US used to be lined with Ash trees, as they were inexpensive and fast growing. Now there are areas where almost every tree has been cut down because of the Emerald Ash Borer.

I think the blame can be assigned as much to the consumer as it can with the individuals growing the plants. Consumers, (myself included) are extremely picky about what they will eat or buy. Varieties of crops are selected for their looks, and varieties of crops that are not consistently good looking fall by the wayside.

I don't think this will cause a famine in the first world in the near future, but the poor genetic diversity of our horticulture is definitely an area of concern.