Okay, let me explain from a design standpoint how stuff works.
Remember when Mike Mearls was saying after the second playtest packet that the fighter was "in good shape"? He meant it. He thought they had the basic idea and general mechanics worked out. Then further design and analysis happened. They've gone through dozens of versions of the fighter since then--only a fraction of which we've seen, and the current version doesn't look much like the second packet version.
You can't just add rules and change select subsystems without altering other parts of the game and having to go back and revise them. You just can't do it.
If you haven't done game design, you probably have no idea how many ideas get a reasonable level of development, seem right, and then are totally scrapped, taking with them other systems that were connected to them. Skilled design can minimize the collateral damage, but not eliminate it. It's just part of the process.
When they have all the content they have planned for the PHB, DMG, and MM, (including core modular options) locked in, at which time they will also have preliminary work on additional books and subsystems well on its way, then they have the game sufficiently prepared that they could put out a basic set prior to putting out the 3 standard books, without much fear of changing the game between the basic set and the standard books. Not before then.
I'm not sure how far along the internal playtests are--but the fact that they are still looking at the results from a massive public playtest survey, and that they actually do change the rules in response to these surveys, implies that the design is still very much in flux. Some parts of the system are pretty locked in. For instance, they are unlikely to substantially change the quasi-vancian casting, the basic rules for attacks, checks, and saves, or the general concept of feats. There are other things, however, that very well might be completely revised. Take the skill system that has gone all over the place, the ranger who wakes up a new man each packet, or races that we have been arguing about for the entire playtest, and just this last survey were finally asked about individually after not mentioning them for close to a year!
Part of playtesting advanced modules (the ones that won't come out with the PHB, DMG, and MM) is to see if they will work with the standard game. They are going to have to test some of these before they set the standard game in stone, and then they have to refine the details of the standard game.
How long will it take? I can't say, because I'm not on the design time (or internal playtesting). But I can say that anything before GenCon 2014 is going to be unpolished offal. If they are doing a good job (which they are capable of) they can probably pull it off by Christmas 2014. GenCon 2014 would be a real gamble.
If we give them enough time, I think we'll be pleasantly surprised at the quality of the rules, even those who personally don't favor them. If they rush it, we'll get crap, even to those of us who favor the direction of the edition.