The biggest losers will be the Gulf Coast refineries and the public at large.
GC refineries are presently augmenting their oil(sands) inventory from Venezuela and ocean transport is far more expensive in the long run.
The public angle is easy enough to understand
This is what baffles me... Oil from the Dakotas (and Montana for that matter) will be in KXL. Presently, the only infrastructure to transport is rail, and this price point of a bbl is at a level that bakken producers may decide to shut-in production until the price strengthens.
All the same, politics screws things including this issue