Amazon have posted up some advance listings of some Kreo items that haven't been revealed officially yet.

A Custom Hound, suggesting that a second wave of the Customizable Kreons are coming.
A Predaking Attacks Set, which could be a proper build set for Predaking.
And an activity book that comes with a bonus Kreon (like those Star Wars Books having bonus minifigures). The Kreon is likely to just be Optimus though.