First of all, imho, Teck does alot of their planning based on long term projections. I heard Don Lindsey on BNN mention that their strategy is to develope/acquire projects that will sustain several business cycles of payback- the longer the better as this allows them to capture years of high revenue from higher commodity prices. SC fits that criteria very well as it demonstrates decades of future mining life.
Secondly, long term projections are for Cu prices to rise not fall - this is what Teck is projecting as well as other major mining companies. And third, Teck is a relatively higher cost producer of Cu at the moment. Projects that allow them to reduce their net cost of producing Cu can only be beneficial to them - again SC fits that criteria.
And forth, all mining companies including Teck must replace their resources otherwise they will go out of business again - SC fits that as it is a huge huge resource. Taking all these factors together, I don't see any chance Teck will walk away from SC.