I don`t know, but just as a thought on the subject. Federal is now owned by ATK industries as are Speer, Alliant Powder, and Trophy Bonded. it could just be they have decided the TB or Speer bullets fit the same nitch as the Nosler did and are staying with their own in house product now. I know this "should" result in haveing a better handle on QC and will be cheaper in the long run.
Then too Winchester isn`t marketing the T/C bullets manufactured by Nosler any more either. Nosler could be dropping out of the supplier side of the business and going exclusive with their own line. Nosler now markets a line of "Custom Ammo" with their own bullet, and brass components for sale.
As I said I don`t know the reason, this is just speculation on my part.
http://www.noslerammunition.com/