This is the future - whatever power plant wins out - hydrogen, electric etc - there is a lot of potential to refit existing motorcycles and cars with new alternative hydrogen/electric power plants.This strategy makes a lot of sense - e.g. replacing the globes current fleet of vehicles with an entirely new fleet of electric/hydro powered vehicles in an attempt to reduce carbon emissions would be self-defeating - e.g. in the light of the huge amount of carbon that would be generated in a relatively short period (say a decade) by the manufacturing process.
The idea of refitting conventional machines with alternative energy power plants was mooted by Rupert Paul in Bike magazine a couple of years ago.