if we are headed for a one world government, this would be a natural step. it is interesting that prophecy, both biblical and other, appears to be being fulfilled. in the past, people had to twist events to make them fit predictions. i don't think we need to do that now. i think i'll buy more VeriChip stock :-)
i have argued against this conspiracy theory in the past, but there are pressures that could bring it about. the rapidly growing Latino population would not be to upset if the borders were opened/gone. they have an ever growing impact on policy. the only thing i can think of that would make the Canadians go for it, is a security issue. there are certainly problems in Canada that could lead them into a security problem. in general, Canadians are more left leaning. they have more of a UN view of the world than we do.
why would we do it? i see no advantage to us. opening up to Mexico and all it's problems would be a disaster. some states would be burdened by open borders. i can't see how we'd do it without hefty amendments to the constitution.
the conversation has been had in academic circles. in fact, i think it was a Canadian who first publicly supported the idea.
i don't think it will happen in the near future. look how long Europe has been at it.
there is one other scenario: if the US were to suffer a massive attack and people needed to take shelter in other countries. i don't think that an attack on Canada would do it, simply because they don't have many people. we could absorb or assist without major reorganization. perhaps an attack on Mexico would do the same. both Canada and the US would need to be open to refugees. Mexico has resources and nutball neighbors.