Picking up on Danny's argument (#168) about non biogenic sources of hydrocarbons and a belief (faith?) in the market system where higher prices will bring increased exploration for hydrocarbons, I would argue that hydrocarbon fuels will remain "desirable".
The energy density of hydrocabon fuels trumps alternatives for mobile systems.
Note that I'm not arguing about fixed plants, where such systems as fuel cells may well work, only mobile.
Challenge John T Hoagland to a bet on this prediction!