It's not about the range
Aaaaaarrrgrghhhh! Will you lot PLEASE stop focusing on the range. Hauliers don't buy trucks based on range they buy trucks based on lifetime cost per mile.
Yes, some are long-distance hauliers and range is important.They can continue to buy diesels.
But there are many others who have trucks that are used all day every day on multi-drop deliveries that get nowhere near the proposed range limit of the Tesla. RHA figures for 2016 gave fuel costs for a 44-tonner at 48-54 pence per mile. The cost of a battery recharge will be half that. They'll sell like hot cakes.