Oil is a non-renewable resource. Extraction costs increase exponentially as readily available supply decreases. Technology exists to build vehicles that are powered by air or water. The oil companies don't want you to know about them.
As fresh water costs continue to increase, it will finally be cost effective to build desalinization plants. Many have already been built in Israel and Saudi Arabia. The oceans won't dry up for a long long time as long as the water cycle continues. The world's not going to come to an end soon, folks! Adaptation combined with technology will keep us going !