At this point, the announcement is just a formality. This week, Katie Couric is expected to acknowledge that she’s leaving CBS Evening News after five years, a departure that has been talked about for weeks. Then, once she returns from anchoring CBS’ coverage of the royal wedding, she’s expected to announce her successor. The most likely heir is Scott Pelley, a correspondent for 60 Minutes. Speculation about Couric’s departure has swirled for weeks, with Couric refusing to say anything about her plans. As recently as April 13, she still insisted she hadn’t decided whether she was staying or going.