The oil was going to be cheaper to route south because they did not have to pump it over a non-existent pipeline in the Rockies. The Keystone was never designed to deliver oil to the US market, just to the ports and then export, primarily to China.
Apparently not enough people foresaw the advancements in fracking and the resulting surplus of US oil. And everyone knew Iran was not going to be able to export oil, whoops.
OPEC and others are desperately trying to get the prices back up. The
breakeven costs for oil production are way over $40/barrel for most of the world. The tar sands of Alberta are not like the fracking in the US.
The tar sands require a lot more startup and maintenance than the fracking and can't just be put on hold as easily.
But regardless this should be in politics.