Delay has been the watchword of the OED from the beginning. Its first editor, James Murray, signed on in 1879, hoping to finish the project in 10 years. When he died in 1915, the job was half-done and the dictionary wasn't published in full - as 10 volumes - until 1928, half a century after Murray began and 70 years after the idea was proposed.
OED2 in 1989 was 20 volumes. If OED3 were published, it would be a 40-volume work. And the question has to be asked: why would you want to publish such a thing? It would look good on a bookshelf, though it would need to be a stout one, and the cost would be astronomical.
Even the first edition of the dictionary was something only libraries held. As a 9-year-old, I spent a winter afternoon in the Hamilton Public Library with my pop-music-mad brother preparing an entry for a radio station competition to compile the most number of words from the letters that made up "the Beatles".
We fancied we had dreamed up some formula whereby every qualifying word in the language, including the terminology of gunsmithing and medieval necromancy, would work its way to the surface. I can't remember finishing the job. (These days you'd use an online anagram solver for the task - I just conjured up 1406, though some of them are fanciful; the OED hasn't heard of "bastelt" or "settale").
The point is that the complete OED in print form has a pretty small target audience. The 1989 version retails now for about $1900; the new one would cost much more, even without inflation-adjustment.
You don't need me to tell you that accessing information has become a lot easier since 1989, when I had to go to a library to check when Queen Victoria died or find an up-to-date population figure for Melbourne.
The internet has also enabled anyone to have the OED without building an extension on the house (and we are particularly privileged: this is the only country outside the UK where you can access it online free of charge if you have a library card).
Online publication also means it's easy to update, of course. Information stored in book form starts decaying the day it is printed. The latest annual update to the OED comprised more than 900 words, phrases and senses. Many are scientific, but "bestie", "Blu-Tack" (as noun and verb) and "bookend" (verb) were there too. Waiting 50 years for a word to get in the dictionary is not so much last-century as Victorian.
In the end, I suspect anticipatory mourning of the end of the printed 20-volume OED is a sentimental reaction by people who would like it to be "there" even though they never use it. My American friend admits he never touches one.
My two-volume Shorter Oxford doesn't get its spine cracked much these days, either.
I can discover that to Chaucer "dangerous" meant "fastidious", without crossing the room to the bookshelf, even though the exercise would do me good.
