I picked up his most recent book for my own ends while doing my Christmas shopping. I like it; full of diverting stories on the background of the words, which helps in retaining them. Part of the attraction to the wider reading public is the nostalgia of lots of the words, and sometimes the ‘threatened’ state of them is secondary. Der Kummerbund (hmm, is a compound word of Persian roots used in Urdu really from Hindi?) is still known to those who have anything to do with the item of clothing; die Dirne comes up in a Rammstein song about Moscow, so it’s proportionately well—known among Russian fans of their industrial metal, of which there are many.

I must admit I only knew cummerbund in English. OED says Persian and Urdu. I haven't looked at this since April last year - it looks as if the competition is new.
A lot of those words are fairly recent slang or facetious. And I find it hard to believe that Groschengrab was the original term for a slot machine - sounds like Berlin slang to me.

I don't think he's necessarily saying Groschengrab was the original term, just that it's been displaced by a different one. It could be a colorful bit of Berlin slang he wants to preserve.

My most favorite endangered German word is "Pustekuchen". I've seen it translated as "Not a chance!", but I think that covers only part of its meaning. Members of my generation react with "Pustekuchen!" when something not too important didn't work because of unlucky circumstances. There's a light sense of regret in it, probably as in "what a pity". I use it quite often, but a student of mine has told me recently that it's out of date and that today's youth says "Wassereis" (literally: waterice) instead of "Pustekuchen". I still don't know if he made that up, but a little survey among my other students showed that no one knew the term "Pustekuchen", so at least he was telling me the truth about the dying out of "Pustekuchen". Apparently, I'm getting old.

My big German-English dictionary translates it as "fiddlesticks!" -- which is even more antiquated.

All those generalizations across all of German. Grmbl. None of the words mentioned above have ever been used in Austria, for example.

My understanding is that Austria is very rich in 'non-standard' vocabulary. Is there any trend towards loss of this vocab in favour of standard 'German', or are distinctive Austrian usages thriving as ever?

Yeah, I'd like to know too.

My flatmate lived in Vienna for eight years and has no shortage of things to say that people who speak Piefkinesisch don’t understand. And, David, die Dirne? Never been used in Austria? Really?

My understanding is that Austria is very rich in 'non-standard' vocabulary. Is there any trend towards loss of this vocab in favour of standard 'German', or are distinctive Austrian usages thriving as ever?

I disagree. Austria and Germany have (slightly) separate standards. (Plus, within either country there are plenty of regionalisms that people think are standard but aren't.)

And, David, die Dirne? Never been used in Austria? Really?

Oops! Wanted to mention it originally, but became too tired... The diminutive, with -dl instead of -e, is my grandmother's normal word for "girl". The word is also preserved in the extreme north (Plattdeutsch). In Standard German, however, it means... prostitute.

I know piefkinesisch, but in my *blush* active vocabulary is piefkisch. The country, however, is Piefkonesien, apparently expressing the barely subconscious wish it were as far away as Indonesien.