In the long run, the PMs comments will be proved correct, either because at some point the oil sands will be exhausted, or other sources come on line that make them economically infeasible.  Already we are seeing drops in the prices of energy produced from other sources such as sun, wind, or geothermal.  This is to say nothing of conventional oil that costs a fraction of the price of oil sands output to extract.  

Entrepreneurship, government support and technological change will ensure this pattern will be sustained.

I know some people have construed the PMs comments as a lack of support of oil sand development here and now, but he has already explained that this was not what he meant, and I think most people get the bigger picture as I do.