But while Flanagan's departure from the outlet, which can be heard at 102.3 FM, is being framed as a retirement after decades of broadcasting, he doesn't preclude the possibility that he'll find himself behind a microphone again.
"It's an age-appropriate time" to split, Flanagan says. "But you never know what's going to happen next."
Experience has taught Flanagan not to be surprised by the twists of fate. After all, his OpenAir run is actually his second stint with Colorado Public Radio; he spent most of the 1990s as part of its classical service's staff.
"I joke that CPR is my ninth and fourteenth radio station," he notes.

Mike Flanagan at his first radio station, KWSH in Wewoka, Oklahoma, where he worked from 1966 to 1968.
Courtesy of Mike Flanagan
KWSH still exists, as can be seen below in a photo of Flanagan snapped during a recent visit to Wewoka.
His school-age stint with KWSH led to other radio gigs in Oklahoma, including employment at KOFM in Enid. Then, in 1974, he and his wife moved to Colorado — but at the time, "I was out of radio," he says. "It's interesting: It seems like I had a 52-year-long career, but I got mad at radio twice and left for seven years each time."
Indeed, Flanagan has five published books, including The Complete Idiot's Guide to the Old West, and has written for a number of publications, including the Denver Post, where he penned a long-running column, and Westword. "I think I was in the second issue ever," he points out about this very publication, which was founded in 1977.
But Denver radio listeners would eventually become very familiar with Flanagan's voice. From 1981 to 1984, he worked at KFML, a legendary station once heard on 1390 AM and 98.5 FM. And he served as a classical announcer on Colorado Public Radio for eight years, beginning in 1991.