Once the pride of Japan, Sony is now a cautionary case study in complacency and mismanagement. But its latest stumble could turn out to be great news for the world's No. 3 economy.

The former tech icon is about to get dropped from a stock index created in January to showcase Japan's best and brightest, Bloomberg News reports. Brought to us by planners in Prime Minister Shinzo Abe's orbit, the JPX-Nikkei Index 400 offers investors access to companies that boast high operating income, returns on equity and market value. By offering easy access to Japan Inc.'s sexiest parts, the bourse aims also to shame executives into revamping failing business strategies and increasing wealth in Japan.

In this case, bad news for Sony CEO Kazuo Hirai could be a plus for "Abenomics" in three ways. One, it would show there really are no sacred cows in Tokyo — signaling that clubby Japan Inc. may finally be ready to experiment with the meritocratic ways of the West. Two, it shines a spotlight on the need to improve corporate governance — something Abe talks about, but hasn't yet tackled with sufficient urgency. Third, Sony's fall from grace is the public smack Japan's flagging exporters desperately need.