Hopefully the NDA will end after the 3DS XL releases.
I'm thinking we will get a Wii U oriented Nintendo Direct at the latest two weeks after the XL launches. That would take it to early September which seems like the time to release big information for a November launch. Places like Game Stop won't even take pre-orders until the price or date gets announced and it seems like Nintendo would want the Wii U campaign to begin at retailers by the first week of September at the latest.