Remember, this is a rumor. Take it with a fine grain of salt!
If this turns out to be true, then there is NO hope for SimCity 5.
List of studios and their known/expected games, courtesy of Nirolak.
BioWare: Generals 2, Dragon Age 3
DICE: They have something that’s not Battlefield, what it is isn’t clear.
Danger Close: Medal of Honor 2
Visceral: Dead Space 3, Army of Four, Dante’s Inferno 2, at least 2 new IPs
Maxis/PlayFish: Sim City Facebook
Respawn: New IP
Insomniac: Overstrike, Outernauts
EA Partners: Populous
Criterion: Hot Pursuit 2
PopCap: They are presumably doing something.
EA Canada: FIFA 13, NBA Elite 13, NHL
Tiburon: Madden 13