hybrid physx and mantle

That no longer possible when nvidia put the 'block' in their drivers. The work around was to use hacked nvidia driver but the way I understand it the hack is driver specific. Means if nvidia releasing new drivers new hack need to created tocwork with the new driver. AFAIK the hack no longer being updated since game using gpu accelerated PhysX is very few making constant update for the hack are not worth the hassle. Also with nvidia gpu becoming much more powerful in some cases dedicated PhysX card are not really needed.

With PhysX 3 being more optimized for multicore cpu developer probably opt that instead of using gpu PhysX. The recent example was The Witcher 3 where there is no gpu based PhysX being used in the game at all. All the effect like destruction, hair and furs were calculated entirely on CPU instead of GPU like past games.