Crain’s New York Business: MTV and Nickelodeon have each been in a double-digit ratings slump for months as their revenue and cultural cachet have languished. Those problems help explain why parent company Viacom is cutting its New York workforce by 264. But as the media giant says goodbye to top execs and restructures its divisions, some media observers think its troubles are far greater than they appear. And not just for Viacom, but for the television industry as a whole.