Sony still has some bundling options in their back pocket, too. They still haven't released a standard WWII bundle and considering how much Horizon has sold, bundling the PS4 with Horizon Complete Edition is another viable option. I'm surprised that Sony has not done the former already considering how well COD WWII has been selling.
The only thing I can think of is it was part of their agreement for the SWBF2 bundle, so Disney/EA wouldn't see as much competition from other PS4 bundles. It just seemed like they didn't do too much to push sales in Dec, other than lowering that bundle to $249. If they had more varied bundles at $249, it definitely could have pushed them to a much better Dec. Probably 1.2M-1.3M.