Well, that's why I said "I think" that it will be coming out at GenCon 2013. I don't know of any official announcement. But my personal guess is that it will come out then.
By the same token, saying that it will be "at least two years" until we're playing D&D Next in its official form is speculation in the other direction. We don't know one way or the other, but I'm not going to be hasty in dismissing the (in my opinion, likely) possibility that D&D Next will officially launch at GenCon 2013.
Sure, while it is entirely speculating, my opinion is that they will be late. I actually *hope* that they will be late, take their time to get it
right, rather than rush it and make mistakes.
Could it be a while longer until 4e-style modules become available? Maybe. But in order to keep their current player base involved in the game, I'm guessing they want to have that stuff ready at launch. It's not ready in the playtest now from what they've said, but I'm guessing it will be a priority to have it ready for actual launch.
I actually doubt that this will be the case (just my opinion, of course). They've still got the 4e players playing 4e and all the tools still in place. I'd be very surprised if 4e style modules were released at launch. In fact, the way they've been publicly throwing 4e and its concepts under the bus lately, I'd be surprised if we ever see a satisfactory "4e-style" gameplay module.
I think their priority, the way they've been talking, is to get the players of prior editions on board first, then worry about their "current" customers. Only time and the market will tell if chasing these customers is a good idea or not.
I should point out that I started out
really excited about 5e, and now, after seeing what they're actually focusing on, simply don't care. I am now of the opinion that it will be out when it's out, and I will judge it accordingly. I'll gladly playtest it and send in my feedback, but I'm not expecting miracles anymore. Less disappointment that way.