Oil is the best liquid fuel that is available. It has far more heat value per gallon than propane, and ethanol. As far as ethanol is concerned you would need all of the arable land in the country and you would still not be able to meet the demand for liquid fuel and in the end you would have an inferior product that is also corrosive and creates problems in systems.
Our principal uses of oil are transportation, heating, and power generation. Natural gas is much less polluting than oil and can be easily used in stationary applications. Such as space heating and power generation. With a concerted effort we could convert 100% of those needs to natural gas.
In addition to using natural gas, power generation can employ a variety of generating methods including solar photovoltaics, wind power, river flow generation, conventional hydro, and yes, nuclear. In the development stages are electrical generation systems that will create even newer means. It is feasible with known technology we could eliminate oil for electrical generation
However the same cannot be said about transportation uses of oil. Other than a relatively small number of electric and hybrid powered vehicles, cars, trucks, diesel locomotives, and airplanes need liquid portable fuel. You can make the argument that trucks and cars can use natural gas, but that too would require an enormous infrastructure.
Electric vehicles and trains are the only way to reduce or eliminate oil for surface transportation. The sources of electric generation are myriad and none of them would use oil. A big part of that transportation will no doubt be Maglev. More on that later…