Americans are thirsty. They all carry big straws. They will suck anything, including bitumen out of the toilet. The world is close to "peak oil". This doesn't meant there won't be any more oil. It means that the "flow" of oil is not likely to increase any further. It's the size of the tap, not the size of the tank. It is difficult to extract unconventional oil at high "flow rates", so it is not going to happen. Tar sands help, but they are not a worldwide game changer. Beware of Americans with big straws.