CIBC World Markets has released a report on the expected growth of oil sands production. They believe that the CAPP estimate, which is the de facto standard, is conservative. Rather than increasing by 1.4 million barrels per day, CIBC believe it could rise to by 2 to 2.5 million barrels per day between now and 2020. That would mean total production of between 3.4 and 4.1 million barrels per day, compared to CAPP's estimate of 3 million. The Globe and Mail points out that the producers themselves have even more optimistic forecasts in the range of a 3.5 million barrels per day increase.
This is just from the oil sands (mining and in-situ). CIBC expects total production from western Canada to exceed 5.5 million barrels per day by 2020, which apparently includes a generous portion of tight oil production.
If production does increase to this sort of level, it suggests industry fears about a pipeline capacity bottleneck are justified. At the moment there is room to spare, but adding millions of barrels of exports would be impossible if Keystone, Northern Gateway or similar pipelines aren't built.
Reuters also reported on this story, but they screwed up the numbers so badly that it's probably more confusing than helpful.