To my knowledge, there is no Hunger Games prequel in the works, and as for Jeff Kinney, he's too busy tackling the subject of young love to turn his attention to dystopian rebellion. (No conclusive word yet on whether Team Greg and Team Rowley shirts will be apropos.)
In non-April Fool news that isn't very new, the children's and YA literature field is wide, wild, and wonderful. My weekend included a viewing (and lots of selling) of The Hunger Games; lots of children's lit talk with students, fellow alums, and faculty at a Simmons potluck; and a mass (and I do mean mass) appreciation of all things Pigeon, Elephant, Piggie, and Knuffle Bunny when my own Brookline Booksmith hosted Mo Willems.
There was at least one child reading The Hunger Games in the signing line. Don't Let the Mockingjay Drive the Bus? It can't be far behind.