That is certainly a looming question. As we continue to develop "alternative fuel" vehicles and more people buy and utilize hybrid or electric cars on our roads, the revenue stream from petroleum based fuels will diminish. Bipartisan, creative thinking will be necessary to come up with innovative and fair tax streams to replace the current system. Currently, hybrids still use petroleum based fuels, just a little less fuel. Loss of gasoline taxes will end up being somewhat of a minor part of the overall problem of conversion to "alternative based fuels" for autos and trucks on the highways.