I have done some in depth calculations regarding this question and to my best equating I figure about 47k dead americans. This sum is co-equivalent however with the number of 9/11 or greater type events that occur in the near future. If that many of us die in one event the final equation is equivocal. If three events are required I'm pretty sure actual immigration reform (more like revolution) will definitely occur. If only one major event is the scenario I belive the number of deaths will have to me over 60k.
A caveat: The only really questionable variable in all this is whether the American people will wait around for government action. Snipers in the streets and mosque burnings may occur first.