Forgeworld have put the Monstrous Arcanum up for pre-order on their site!Monstrous Arcanum pre-order
It contain 32 new monsters, and at least one of wich is for us Tomb Kings (probably the only one though), the Khemric Titan (formely know as Khanopic Titant)! The description says that these beast can be used outside of Storm of Magic, as the book inclus rules ans scenario to use them outside of SoM games.
Personally I'll wait to see when they release the Titan, and if I like it (and if it's no a $300 model!) I'll probably get both :)