So are they doing something new with the engine where it will move calculations over to second card but its not considered accelerated?
I usually prefer to stay with definition: "the game is considered to be hardware accelerated, if precense of supported hardware adds a noticable difference in performance and/or quality (quantity) of physics effects or content"
I've played several parts of Witcher 3 with GPU acceleration enabled and disabled from drivers, and haven't noticed any real difference in performance or content (quantity of cloth objects, for example). Also, there is no option to switch acceleration from game settings.
Thus, I consider the game to be "CPU PhysX with extra VisualFX effects"
Similar way, you can sort of enable GPU acceleration in UE3 besed games by editing .ini files, but that won't make Mass Effect or Gears of War a GPU PhysX game.