True, they may not be available in Canada anymore, but it will be really difficult to ban purchasing these boxes from another country. Current Canadian law as I understand it, it is not illegal to stream content provided from these boxes as you are not making a copy. It is downloaded, viewed in 'real time' and disappears. It is illegal to download and store a copy.
As far as affecting current streaming, it should have little effect. There are various app on these boxes, and there are great resources on the web that can give you step by step video instruction on how to update and configure your apps, should your apps stop functioning.