For ‘four-channel quadraphonic’ read ‘5.1 suround sound’. So yes, that has come true, albeit in a different guise.

Lightweight cartridges tracking at 0.1g with radioactive stylii - no.

Tuner-amps (receivers) being in the majority - no.

7" discs, cut by laser, and one third the standard thickness of vinyl, giving a playing time of over an hour - no. (But something similar did happen with the 5" CD)

Predominance of speakers using electrostatic mid-range and electrostatic tweeters - no. Electrostatic speakers are still in the minority.

Dedicated acoustically treated listening rooms becoming more prevalent - maybe, but only for the determined enthusiast.

Continuation of tape, either cassette or open reel, as a source - no.



As others have noted, there was no mention of digital techniques and their development. It might seem surprising that an audio journalist may have not known about the developments, but it is quite possible that manufacturers were keeping all work in that area secret until they had something ready for the market. That didn't happen until 1982

So all in all, the predictions have not materialised. However the correspondant was looking 33 years into the future. Look what has happened in the last 15 years.

What did Nostradamus have to say on the matter?