There are forms of biomass which are more prolific than others. Giant King grass, for example. Or various forms of micro- and macro- algae.
We will also see some amazing technologies for converting carbon resources (including biomass) into useful fuels. The name of the game is efficiencies and useful yields. Expect significant improvements in both over the next few years.
Gasification, fast pyrolysis, and torrefaction are all competitive now -- and getting better fast.
And while most people are looking toward cellulosic ethanol, and waiting for higher yields of saccharides from cellulose and hemicellulose, clever people are performing an "end-around" the cellulosic bottleneck. Looking beyond ethanol will be best for the long run, in any event.
Biomass can be grown at will, almost anywhere on Earth. The profits from bioenergy will be distributed far more widely than those for fossil fuels, so that while fewer people will grow super-rich, far more people will be able to enjoy productive and comfortable lives from the proceeds.