Thinking about it some more I think the best chance of surviving into the medium term is some cataclysmic shift in exchange rates (maybe not so improbable given the Japanese Government debt). An effectively free drop of 20% in Japan based costs would give quite a massive boost that might give time to attack other problems but isn't enough on its own (assuming Sony's debts are in Yen as the value of many assets would also fall which could put them under before they could benefit from trading against the stronger currencies).

Japan printing itself out of debt might be quite a good move although clearly not without its costs amongst savers.

Anyway getting well out my expertise here.