To remain a global leader, Japan needs to open up immigration to accommodate its aging society, possibly to the point of allowing 647,000 immigrants to enter annually until 2050, a new study shows.

The study, "Reinventing Japan: Immigration's Role in Shaping Japan's Future," was written for the Carnegie Endowment for International Peace by Demetrios Papademetriou and Kimberly Hamilton.

Japan is poised to sink or swim, the study argues, and must open up to more permanent foreign workers "across the entire jobs continuum."

These changes will ultimately lead to fundamental alterations to the social, political and legal systems.