Maybe the show should end after 50 years. I mean for a show to last this long is amazing,but It's starting to look like time has caught up with Sesame Street and it's slowly becoming non relevant to today's pre schoolers.
I don't think the show would be let go so lightly. Look at how much hoopla the news breaking of older cast members being "fired" caused, especially to those who haven't watched the show in decades so they didn't know they were quietly phased out. As soon as SW would report "50 years is a long time to run a kid's show, time to pack it in," there would be such an outpouring of anger directed at them, they'd backpedal and make plans for the next several seasons after that.
Sesame Street is too much of a cultural institution for it to go away any time soon, and SW clearly cares about the preservation of the show at any cost. It's just that we don't like what the "at all costs" usually results in. Personally, if they made it to 40, they have no signs of wanting to end it until the world does. I could have seen them giving up after season 30, and be replaced by a long line of mediocre kid's shows we would have all forgotten the names of that don't even have the cultural impact a mid to late 90's Fox Kids cartoon that gets canned in half a year for extra Power Rangers rerun slots. A statement coming from someone who's a huge fan of Ned's Newt, Mad Jack the Pirate, Toonsylvania (which had a Burger King tie in at least), and Secret Files of the SpyDogs. Anyone remember any of those? No? So instead of Gary the blue puppet walrus or early CGI cartoons about sharing, Sesame STreet chugged on.
I don't think reduced usage of older cast members is enough to say "time to pack it in," considering the intended target audience only watches the show for 3, maybe 4 years, sometimes with their parents paying attention to them. it's more like SNL than The Simpsons. The different comedy and comedians speak to younger audiences while those who grew up with Murray, Akroyd, and Curtain stopped watching when they left (and put in Dana Carvey and Mike Myers or Will Ferrel and Amy Pohler and it works
just as well) stopped watching the show, even occasionally.