Did you see that cgcookie has announced the launch of a Blender Market for this summer?
I’m really excited, as I hope this will help improve the Blender community. I think it could complements the Unreal Engine Marketplace (when they will be both open).
Also waiting for the very near release of the improved FBX exporter to integrate better with UE4 
“Buy and sell production-ready add-ons, …]”
****, what? Blender is awesome and popular because it’s free and open source. And appearantly, they now plan to end that and split it into two groups, the one that can afford the useful add-ons, and the one that can’t?
Blender add-ons are Python scripts that have to be GPLed licensed (this is indeed in their Market FAQ) so I would not expect too many attempts to sell them 
What I expect is quality content.
I am personally waiting both Unreal Engine Marketplace and Blender one to provide textures, materials, and meshes packs.
Cheers