Senior Producer Jason Bergman had this to say on a Bethesda Forum
We just wanted to drop in here and let you know that due to circumstances beyond our control, Lonesome Road won’t be out this month. This isn’t due to any major issue with the code or content, but there are lots of factors involved in releasing these things, and one of those is causing us to slip past our intended release date.
We don’t have an exact date yet, but we’re working to get it out as quickly as possible. We’ll be announcing the final date, along with a couple of other interesting FNV-related items in the near future.
The teams at Bethesda and Obsidian”
However they did release the first image for the DLC.
Exciting isn’t it?