[IssaRice]

Sure, that's reasonable. This is a specific "slippery slope to open borders" as discussed here: http://openborders.info/blog/slippery-slopes-to-open-borders... . The relevant "slippery slope" is:

"Gradual expansion and merging of free migration zones: For instance, the EU is a free migration zone for European countries, and it is gradually adding countries. Suppose the United States and Canada created their own free migration zone, Southeast Asian countries created their own free migration zone, and a few free migration zones emerged in Africa and Latin America (South America). The US-Canada free migration zone could, after some time, add Mexico and the Caribbean Islands, and then merge with the South American free migration zone. The European free migration zone could eventually merge with the new unified American migration zone. Over time, as the threat of terrorism, and the subjective sense of the threat, receded more and more into the past, the Gulf states could merge with the European free migration zone. And so on, until eventually the whole world would be a free migration zone."