It was announced a couple hours ago on the AC Facebook page.
The first Volume of Assassin's Creed: Last Descendants is out to order over at the Scholastic's page. HERE.
There is also an option to read the prologue. (First 15 pages of the book.)
{I haven't read it yet, I'm still racing through Underworld. I should be done with it and onto this one tomorrow, though.}
Also, the name of V2 is stated to be"Tomb of the Khan".
{And, that's all. I do have to say the synopsys they gave for the 2nd book spoils the plot for the 1st one a lot. Still, gonna read it, though.}