The Ryzen CPUs will all be on the new AM4 motherboards, and presumably that platform will last for at least a few years, so it seems like there should be good room for future CPU upgrades. And if you're asking if CPUs in general can be upgraded, yes, they can be removed from the motherboard and swapped with a new one. So long as new CPUs continue to get released for the same motherboard socket, or higher end chips from the same generation are available, you should be able to upgrade to them. However, you can't swap from say, an Intel chip to an AMD one, if that's what you're asking, unless you replace the motherboard as well, since they use incompatible motherboard architectures and sockets.
And yeah, I checked Canadian pricing, and the current lowest-priced 8 core, 16 thread Ryzen will be over $100 CAD more than your current pick. Apparently, the mid-range Ryzen CPUs will come out sometime in the second quarter of 2017 though, and it's likely that a 6 core, 12 thread Ryzen CPU won't be much more than your currently chosen one. If Ryzen's per-core performance is at least comparable to Intel's, that might be something worth waiting for. Or even if you decided to stick with an Intel build, it seems possible that there may be some Intel price cuts over the coming months to better compete with AMD's chips.