There was a book where the White Scars had to fight psychic Kroot. The Kroot got the power from eating Eldar.
The only change I want to see for Kroot is them getting better technology instead of being viewed as savages. Basically stealth suits made for Kroot, giving them superior firepower and CC capabilities. Since the "play tester" mentioned an assault suit with no names and models, it is possible.
"Snooki gives birth to Heavy Gun Drone squad, someone says they are over powered, then the world ends."