Today's rumor does not give us specifics, but mentions the types of units that will be coming in the next release for Necrons.
As always please take with a grain of salt, and note that this rumor is about a week old as I post it. (sorry guys I missed it)
Couldn't see this on the thread (although I didn't go through every page!) early next year youll be getting a second wave of necrons - entries in the codex not covered by this release, 4 vehicles, a walker and 2 aircraft, also new tomb spiders IIRC.
Here is a link to pics from the codex on unreleased models.