One thing can not be stretched that far period...............It needs to be like a potluck dinner,a little bio ,a little electric a little solar etc.
There are billions of people drawing on one resourse,it makes it a tall order to replace that fully with one thing,therefore it needs to be diversified ,many different sources at this point,later when a replacement become viable ,then we can all shift to the new viable source....there is no viable source at this time for a full switch,which makes it nessisary to use many things at this point ,just to lighten the load for now.
Solar is looking good now ,with the new panel tech ,such as lining up all the crystals in the panel for a better output over a longer period of time.
Solar is viable now on the housing end ,there is just not very much savings over normal fuel at this point because of solar panel /battery life exspectancy.So not many people want to deal with it for no savings over a 20 year period,even though it would have a trickle down effect of lighting the load on oil based natural fuels quite a bit.
If we only burnt the stuff in autos ,there would be alot less demand at this point.