Lilith and Inarius are making their appearance in Call of Duty: Modern Warfare 2 as playable operators in Season 6.
The official blog post on the Call of Duty website also mentions new Diablo-themed bundles.
Diablo-Themed Operators
The Burning Hells arrives in Call of Duty. Diablo-themed Bundles make their fiery appearance, complete with the Queen of the Succubi Lilith and the fallen archangel Inarius as Operators.