But for the intervention of Mark David Chapman in New York on that fateful day in 1980, John Lennon may well have been celebrating his 70th birthday in October. We'll never know if he would have moved gracefully into retirement, made dance music records à la Paul McCartney or, indeed, taken a deep breath and reformed The Beatles. What we do know is that his legacy remains intact. It's also always been ripe for exploitation.
Which is why it was no surprise to learn last week that his 70th will be marked by remastered versions of his entire solo catalogue, available individually and as part of a money-spinning array of compilations. There's the 11-CD John Lennon Signature box set, the four-CD Gimme Some Truth box set with thematically linked songs, and a 15-song greatest hits Power To The People. There's even a new, stripped down remix of Lennon and Ono's Double Fantasy album, originally released just months before his death. Something, indeed, for everyone, as EMI are no doubt hoping.
Sure, Yoko Ono might well have had honourable intentions when she said: "I hope this remastering programme will help bring his incredible music to a whole new audience." Songs such as Imagine, Instant Karma and Give Peace A Chance are indeed timeless, and Lennon's influence can clearly be heard in the music of Flaming Lips or Oasis. It makes sense for these songs to be packaged up for a new generation.
But it's impossible not to be cynical about such an exercise. EMI and Ono would, without question, have looked on with interest at the incredible reaction to the digital remasters of The Beatles' albums last September, which sold more than 2.25 million worldwide in the first week alone. New records were set for most simultaneous albums in the UK and US charts. Never mind that the new box sets would have set the listener back a combined total of more than £300 (Dh1670) for songs he or she probably already owned and knew back to front.
So are The Beatles, to paraphrase their own work, getting better all the time? Does remastering actually make a palpable difference to the sound or is it just a clever marketing ploy? In the Fab Four's case, actually, it probably did; the music has more punch, and individual instruments are often much more distinct. The Beatles In Mono box set is, at times, revelatory, revealing for perhaps the first time (unless you happened to actually be in The Cavern Club in the 1960s) how visceral and peppy they were.
But in the vast majority of cases, the differences are embarassingly miniscule. Led Zeppelin released Remasters in 1990, with Jimmy Page himself overseeing the operation, rather than a producer or engineer. The results were impressive in their clarity if nothing else. But remastering the Remasters, as Page did with Mothership in 2007, seemed faintly ridiculous. Reviews at the time marvelled at Led Zeppelin sounding "as impressive as they did in 1972". In that case, why not listen to the records made in 1972?
Did it mean that all previous versions of his songs had become redundant? Was the original Immigrant Song now obsolete? Of course not. Listen to those records side by side now and the difference between the originals and the tinkered versions is really just one of volume. Because CDs and MP3s have to compress the detail to make their formats work, subtleties are lost to a clattering mid-range that makes everything sound louder, rather than necessarily better. There's nothing more tiresome than the vinyl apologist, but it's certainly true that many records from that time sound warmer - crackle aside - because they haven't been put through a digital wringer.
And the feel of the originals is important - perhaps not to people who are approaching Lennon for the first time, but to those who grew up dutifully buying his albums. Being a fan of a band or an artist is to love them for all their imperfections, and so to have these ironed out, to be told that the music is only now pristine (as the recent Kraftwerk remasters did) is oddly disquieting. The music becomes excessively clean and clear, which subtly changes the relationship you have with the band. They're no longer exciting, innovative, creative talents who shot for glory in the dark and sometimes failed. They're men in lab coats continually taking out glitches.
The John Lennon remasters will be interesting, then, as an exercise in comparison with the originals. They may even be slightly better. But it would be incredible if they made a genuine difference to his patchy back catalogue. One thing's for sure, though. They'll certainly make a big difference to EMI's balance sheets come October.