The following is pure, 100% speculation, but I think it's fun to do anyway....
As has been posted on numerous threads, the "biggie" coming out of the Annual Meeting this past weekend is that now the "faithful and discreet slave" is considered to be the JW governing body only - not "all anointed nes on earth".
And has been posted, it seems that the most recent direct statement of the "old light" - that the FDS is composed of "all anointed" - was made in 2009.
So that makes me think - what happened between 2009 & 2012 to elicit such a change?
Both Jack Barr & Ted Jaracz - the last of the "old guard" - died in 2010.
The GB went from 9 members down to 7.
Assuming that the "2/3 majority" rule as written about by Ray Franz was still in effect, this scenario seems plausible:
1) In 2009 & before, the vote was 5-4 in favor of changing the teaching to the current understanding - not the 2/3 needed, so it did not change
2) Both Barr and Jaracz would have been in the minority, against making the change
3) After their deaths, the vote would then be 5-2 - more than the 2/3 majority needed to adopt it
4) In preparation for releasing this "new light", statements de-emphasizing the "all anointed are the FDS" and emphsizing the GB's authority were made repeatedly in WT articles for a couple of years
5) Finally, in October 2012, the time was right to announce the change
Of course, absolutely impossible to prove (unless someone does a "Ray Franz" and writes a book) but it at least seems plausible.
... OUTLAW