After browsing through Relic's WH40K Tabletop Discussion treads I noticed something rather peculiar. In the Medusa V stories about some fight with the Necrons the Imperial Guard saw what has never been seen before: a HUGE bug-like machine thing used by the Necrons! That could only mean one thing: Forge World will probably unleash a second mega heavy weapon for the Necrons! Or not, but we'll bave to wait and see about that!
And if you don't believe me, click here! The second page of this thread also has interesting info about what the new Necron Superheavy could be!