I am not really sure what you are referring to. Canada has about 20 non-USA international entry points, mostly at airports. If we want to, we can control the influx fairly easily.
The US is still a first world country, so it's not like we will be getting a lot of impoverished, uneducated third world refugees from the south.
I am, however, expecting another wave of political or economic refugees from the US in the next decade or so. Previous refugee waves from the US have been absorbed and most actually were a plus for Canada. So, I figure it will be a wash or a net plus.
Honestly I wish Canada Good Luck. Americans, to the south of Canada, are finding our waves are controlling and participating in various criminal activities. Americans (be danged and the laws of America be danged) seems to be what the waves (entering) are telling Americans. There has been very little shooting to this point but with all the waves entering and the waves entering are increasing the criminal activity. The likelihood of those entering all being peaceful and intent on NOT harming Americans is diminishing substantially. I do not wish the same for Canada. Good Luck to our Canadian Friends. We are being overrun with criminals to your south.