I've never been into sports talk radio, but I'd be surprised if Mike & the Mad Dog went off the air since it's such a popular show.

Barring a change of heart, the partnership between Mike Francesa and Christopher "Mad Dog" Russo is not expected to survive to see its 19th anniversary Sept. 5, industry sources with knowledge of the situation said.

They may have already done their final show together; their next scheduled broadcast is not until July 11.

It is not clear which host would remain on WFAN, only that it would not be both of them. One factor appears to be a fraying of their personal relationship in recent months.
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 http://www.newsday.com/sports/ny-spmike0622,0,842426.story