Yes demographic shift and bubble economics, this much is true. But Japan is hampered by constitutional restraint of their armed forces, the United States economy (infamously) enjoys much broader support from intelligence and military. Japan also historically rejects mass immigration, which the United States has adopted as a means to replenish low skill workforce and 2nd generation child->skilled worker pipeline. If political power can successfully be wrested from the boomers, the USA can abandon their entitlements and rebound quickly. If boomers hang on to political power: a period of sticky inflation and slow growth.