Will we run out of water before fuel?

You have a good point there. Anyways, I hope that, when fuel runs out/stops being used, people will focus on alternate energy sources...

Scientists are focusing on developing alternate energy sources now. Oil will stop being used only when those alternates are cheaper, or the oil runs out. If we don't have a cheaper alternate energy source by the time oil runs out, we can say goodbye to our life as we know it.