Quite. It wasn't until the Northwest Company and the XY Company (both based out of Montreal) started setting up inland posts and siphoning off the furs that would have gone to York Factory on Hudson's Bay, that the HBC started moving inland, too.Thanks for reminding me. For some reason I had it in my head that they started sending people inland a few decades before the conquest of Quebec, but looking things up again their first inland trading post wasn't established until 1774. It was the French fur traders who founded the earlier inland outposts...
Also. As to the viability of the Prairies as agricultural land, basically until you have John Deere's plow and McCormick reapers, or equivalent, the Prairies aren't really suitable for agriculture outside of river bottoms. Moreover, to really grow wheat you need special quick growing varieties that were only slowly developed. And thirdly, getting grain to market before you have a railroad. Well, have fun.