Biggest issue with hybrid and electric cars is battery technology. To put it frankly, as electricity storing mediums the current types of batteries we have absolutely suck. Their not efficient, they wear out, and their made out of precious and toxic elements. Until someone comes up with a highly efficient battery, I don't see the electric car market going anywhere except for wealthy eco-snobs. If someone were to invent a new battery however, it could seriously revolutionize transportation and automobiles.
Another interesting electricity medium is hydrogen. Hydrogen can be used to basically replace the battery as a energy storing medium - and it's extremely efficient and 99% emission free. As far as the long-term future goes, unless someone miraculously invents a new battery I see hydrogen replacing gasoline as a fuel source.
PowderHound and TreeNinja