This weekend quietly marked the end of an era. On Saturday morning, the CW showed Cubix, Sonic X, Dragon Ball Z and Kai, Digimon Fusion, Yu-Gi-Oh! and a few others for the last time. Next Saturday, the CW will move on to One Magnificent Morning, a block of live-action, educational entertainment for kids. And, believe it or not, that will be it for Saturday morning cartoons on network television. Of course, on cable, animation is doing just fine—Disney, Nickelodeon and Cartoon Network are still putting out all kinds of cartoons. But this marks the first time animation won’t be part of network television’s Saturday morning lineup since the ’60s. Somehow, despite Michael Bay’s best efforts, kids just aren’t as into cartoons as they used to be …