Holy moly. Me dumb would think if there is labor shortage then employers would compete to offer the best wage, work ethics, working conditions, and so on.
That's basically the 'hand of the free market', people will go where they have better condition. Those who retain staff through fear are in for a rough ride, you can't go against human nature even in society like Japan that emphasize abnegation so much.
In other countries what they would do is push for more immigration so that they can remain in dominant position, but thankfully for the Japanese they don't have that issue.
I bet that Japanese labors condition will drastically increase in the coming 10 years.