That’s precisely the entire point of the article. The author concludes by throwing out loose numbers like “thousands” and “hundreds” and conjecturing how that would have changed the outcome of the war. He says the Allies would have still defeated the Axis with its greater industrial might, but it would have taken longer.
Germany only had a handful of U-Boats at the start of the war. Germany might have been able to starve Britain in 1939/40 if it had a large U-Boat fleet as Britain was desperately short of convoy escort ships.