My guess is, and has been, GenCon 2014. I wouldn't be shocked if they released it with a little lead time, but by GenCon.
I would find it hard to believe that they'd spend three GenCons in a row without anything to sell. But I also would find it hard to believe they'd go two GenCons in a row without anything to sell, not even having a booth in the exhibit hall the second time. So maybe my instincts are off.
The Basic vs. Standard question is interesting. If Basic is going to be a boxed set, it makes sense to wait on it because the production time is longer and the target audience is more on the Christmas time frame. The only real reason I can see pushing out Basic at GenCon is because a lot of people would buy it, then buy the core books that may not buy the Basic set otherwise.
Cheers!
Kinak