I just don't think funneling a significant portion of this playing content through stores is going to work.
Just a note on that "Significant Content"...
The adventures that will be available through D&D Expeditions make up a surprisingly small amount of the content that will be available for D&D.
D&D Encounters is just the first part of the published adventure "Hoard of the Dragon Queen".
There are currently 14 announced adventures for the D&D Expeditions line, but they are each a single session (3-4 hrs) long.
Meanwhile, "Hoard of the Dragon Queen" and "Rise of Tiamat" covers 14 or 15 levels of play... which is meant to be about 26 sessions worth. Then you have the Starter Set adventure, which is another 4 sessions or thereabouts.
So, you get about 120 hours of play through the published adventures, and in the first six months, only 56 hours of store-only play.
(And then there may be Dungeon magazine, if it ever restarts...)
There may come a time when the Adventurer's League is giving a lot of content... but it isn't looking like it yet.
Honestly, I'm rather worried about the dearth of material, and I'm extremely worried about using the first section of Hoard of the Dragon Queen for D&D Encounters. How many people are we going to lose from Encounters because they're running it at home at a much better pace? Or just want to complete the full adventure?
Cheers!