I don't see the rationale for waiting until 2014 to hit the 40 year mark.
They'll make decisions based on projected profitablility, the market, etc. etc.
I don't think they'll make more money by releasing it concurrently with the anniversary.
Instead, I think (and hope) we'll see an anniversary product or products. Maybe a D&D retrospective (history of, quotes from designers, that sort of thing). Maybe also a "crunch through the ages" to complement that book, discussing different editions, offering conversion tools and strategies, including perhaps a module or mini module from each edition, or if 5e goes modular, perhaps the same module played with various "mods" and discussion of which edition which mods make it feel like.
The reason I think the above is twofold. One, I don't think they'll put off 5e if they think it can reinvigorate their market. Two, and this is even MORE important...If, as in most edition cycles, sales start to slow about a year in, they can re-invigorate the 5e market with the 40 year anniversary especially with those two products I envisioned (they'd be like advertisements, but, if done well, advertisements I would buy).
I predict June 2013 for release of 5e. I also predict some sort of retrospective 40th anniversary product meant to honor d&d but also to showcase 5e to us grognards.
Hell, one last prediction. On the 40th anniversary of D&D they make the old edition products available again. This will be especially true if my two other predictions are correct ... and if 5e is modular enough to play older editions. That way 5e is released soon enough to not compete with older editions, but then a year later (once most people who are going to buy the core books and try the game have done so) they release the older edition stuff that is somehow all playable with various subsets of 5e mods.
It's about the only way I can see to recapture the splintered market, and would simultaneously garner them massive goodwill.