This was in the late 1990's, then they began a program of liberalized immigration which now in 2011, sees over 30% of Singapore's resident population as foreigners. The influx of so many immigrants over two decades has caused severe strains upon the fabric of our country, a tiny island city-state.
Yet the story remains the same. The new immigrants are unlikely to suddenly produce more children [say three or more] and ironically, if they stay on, they will simply add on the the oncoming demographic crunch since they are mostly working class, and we all know how that particular segment of society is assaulted by growing inequality around the world.
[Most amusing, the incumbent political party which has governed Singapore since our independence has largely expended all its political capital. But that's not really relevant to our discussion on aging + demographics]
I suspect Britons in the U.K can tell a similar story, since Blair & co went on a similar tilt after they got in a decade ago.
Thus, I would caution against the popular view that immigration is needed to avoid the oncoming demographic crunch in societies. It probably can't fix the old issue, and instead generate many huge socio-political issues.
So for me the article presents a non-falsifiable claim: Japan is doing better than ever. However, his claims could be checked by someone in a Japanese manufacturing company.
In the meantime, I don't see why it is surprising that Japan is doing well. As a nation they have positioned themselves well. The major challenge they face -- lack of natural resources -- has not materially affected their growth in the last 20 years. Instead, they are continuing to focus on the entire manufacturing vertical. Not just steel mills and consumer brands (ok, I'm making the U.S. seem dumber than they are).