Mass penetration will take longer. First, fuel cells must be safe and reliable. Fuel cells now have a problem with delayed start-up. And there is the question of infrastructure. Until it is possible to cleanly make, store, and use pure hydrogen for fuel cells, we will need to rely on gas, or compressed natural gas, and to reform them on board into hydrogen to generate the fuel for the cells.
Cost is another problem.
Hybrids can't cost significantly more than similar gas-powered cars. And the cost of fuel must be reduced to near the cost of gasoline. It may be another 10 or 20 years until these elements are all in place and mass marketing becomes possible. This issue is immensely important. And it is why we need to invest in new, cleaner technologies now, so that, over time, we can push the operating costs down and make them available to emerging markets as well.