Bottom line, the US needs the oilsands output in order to desensitize the US from reliance on OPEC and oil sensitive to the geo political influences of OPEC and mideast sources.  At the end of the day, the US will not place any unreasonably onerous restrictions on the oilsands as we need the output of Canada!

Additionally the logistics of supply to the US, meet the objectives of both Canada and the US.  This does not mean  some of the oil sands output of Canada will not make its way to other regions of the world.  It simply means that supply of oil sands output meets the economic, political,  and security interests of both Canada and the US!

All else, ultimately becomes superfluous.

Brian