Enbridge is reversing line 9 to bring western product to Ontario and ultimately Montreal.
TransCanada is converting a portion of their gas pipeline to oil service, probably in the next 5-8 years. That will bring more western product to eastern markets and maybe get out as far as tidewater as a potential export project off the east coast.
Pipelines do play a role but product will go to the market with the highest netback to the producer so sometimes, its not all about pipeline capacity. Thats why you see people using rail/truck/barge to juice their netbacks by taking product to premium markets, despite paying a much higher transport fee (vs. pipeline) to do so and still make a sweet margin. All western barrels want to get down to USGC (hence the reason why Enbridge and TransCanada are both working on projects to increase/twin pipeline capacity there).
Still feels like these eastern projects will get built before Northern Gateway due to all of the NIMBY's out west in BC. Hell, they don't even want Kinder Morgan to expand an existing pipeline. More like NIABY (not in anyones back yard).
Also, better maps here: