Some of the speculation here:
(1) The GB intend to release a new version of the Bible, to be announced at the Annual Meeting in October, and slated for 2014.
I had not thought of that, but it makes sense.
Since we're speculating here, I'll throw in my 2 cents:
I'd speculate that they intended to have a NNWT (New New World Translation) in time for the District Conventions, which after all had the theme "God's Word is Truth". That would seem to be the perfect theme for an assembly where a new Bible is to be released.
However, I'd further speculate that they have run into some snag, and could see that it wouldn't be ready in time.
Why not go for broke in the speculation department - maybe its not a production snag at all, but perhaps there are some "controversial" wording changes, and they'd prefer that all JWs get the new Bible on the same weekend, as opposed to the distribution process dragging out across 3 or 4 months as happens at the DCs. I.e., to cut down on "confusion" and "disunity" everybody gets their Bibles over the same 2-day period (due to space limitations at assembly halls, the AGM parts will be repeated over a Saturday & Sunday).
Who will wager with me that I'm least 75% right on all this?