I think commercial vehicles have the potential to reach a much more sudden tipping point than cars. It's much more a question of economics, and if money can be saved, companies will put up with certain inconveniences, or find ways around them. Unlike individuals, who may buy an EV to make a statement/for environmental reasons, or not buy one in case they at some point in the next ten years want to travel 1000 miles in a day. I believe that most delivery vans in big cities travel relatively short distances each day, due to traffic, loading/unloading, etc. Which should make them ideal for conversion to electric, particularly if supported by incentives to reduce local pollution in urban areas.