@Cycloptichorn,
Yeah, it'd be crazy. I'm pretty upset with how all immigration is handled across the world. The USA is probably no better/worse than any European country. I think people should have the right to live in whatever country they choose, regardless of their country of birth.
I don't think it'd lead to the decline of America. Sure these people will come over here and they will be eligible for the same benefits that citizens get. I don't think that causes any problems. Once they get here, they will pay taxes and pay their own way. Even benefits like social security are based on how much money you put into the system, so an immigrant will receive less money because they put less money in.
I don't agree with one world government, but people of the world should be able to live in the country they choose.