Absolutely, the tar sands is getting to market. The issue, in part, is expansion -- and resisting creating infrastructure that becomes sunk cost in considering infrastructure / energy / investment choices tomorrow and the day after tomorrow.
The rail expansion for export has been impressive to watch. Even so, as you are well aware, that rail expansion is inadequate to support the desired export requirements. Also, in part due to enriching Buffett (further), the additional cost of that rail movement is a drag on expansion plans.
How much of the rail expansion, however, is Bakken oil vs Tar Sands?
It is a serious point that that the EROEI and pollution load worsens due to rail transit. And, as per rail safety issues, there are risks created via increased rail traffic vs pipeline. Although, have there been rail car spills of Dilbit along the lines of what happened in the Enbridge pipeline on the Kalmazoo?
Finally, absolutely a focus 'solely' on supply is, at best, reckless and, at worst, inane. National investments in Steel Interstate, ever-increasing CAFE standards, better land use planning ('smart growth' as misnomer), and other targeted paths to drive down oil demand -- across the planet -- as a path to deal with peak oil and climate change are more critical than efforts focused on the supply side.