You say "good riddance", but given Japan's demographic implosion, is it really a good thing that the immigration flow's gone negative?
A coworker you can’t depend on is no better (and often worse) than nobody at all.
Besides, the foreigners who are going to be leaving are mostly middle-class white-collar workers who, while useful, seldom fill essential positions. A shortage of English teachers (there’s too many of those drones, anyhow) is not going to cause much hardship.
One positive impact (if it can be termed that) is that I expect a baby boom in Japan about nine months from now. It always seems to happen after a disaster.
My beloved spouse who spent the night after the quake in an emergency shelter in Tachikawa complained the next day that she had trouble sleeping because several couples were celebrating the fact that they still lived in the most natural way.
Life goes on. We just have to have the courage to face it.