Once again, this article shows, it's more than just about money. The new management at CBS/Paramount has a larger agenda than just what it broadcasts at 11:35pm. It's the same with the radio network.
Management feels it's on a mission to remake American media. Part of that is to reshape CBS for a time when linear broadcasting is no longer a priority. Part of that is to get rid of the parts it doesn't like because they are liberal (Colbert, aspects of the news department) or old (99-year old radio network). And yes, part of it is financial as well.
If the old CBS was offering Colbert a five-year contract a couple of years ago, how did the new CBS realize the show is losing money? As I've said before, if ABC and NBC aren't talking about cancelling their late night shows, Kimmel and Fallon, then why would the new CBS management cancel #1 Colbert, rather than tinker with the show to cut some of the expenses? No more 200 member staff, no more Ed Sullivan Theater in Midtown. Maybe move to a cheaper venue in Brooklyn, maybe do fewer shows per year with a smaller staff.
And if there are nine radio networks in the U.S. with hourly newscasts, why is CBS the one that's ending in May? Just as NBC and ABC are continuing their late night shows, the other eight radio networks including ABC have no plans to give up doing hourly newscasts. CBS has one of the strongest line up of affiliates, some of the highest billing radio stations in the U.S.: WTOP Washington, WINS NYC, WBBM Chicago, KNX LA, KCBS San Francisco, KYW Philadelphia, WSB Atlanta, WWJ Detroit, KIRO-FM Seattle, etc. CBS can't make money with all these top rated, top billing stations running the network's spots each hour?
Funny that this article says when Colbert started doing Late Night, he was less political but the ratings weren't great. Then he started doing more politics, more anti-Trump jokes, and the ratings went to #1. The thing that made the show so successful is the reason why the new CBS management is terminating the program as Colbert's contract ends.