Isn't their current economy significantly smaller than their current population, the same problem the USA has, but worse? In that case they can either suffer eternally, shrink their population to match their economy, or expand their economy. Apparently #1 is unappealing, they're carrying out #2, and #3 has proven impossible for the past couple decades.

One way to report on the future is to make a "questioning" article that asks what will happen if ... and carefully point out there is no answer. So, much like CO2 emission, this isn't a "if" or "unless" story, this is the inevitable future. Best start thinking about how to handle the Japanese bond defaults, because they're coming. Other than that, there appear to be no real problems at a worldwide scale.