O’Reilly recently signed a new multiyear contract worth more than $20 million per year. When Roger Ailes left Fox News last summer, the Murdochs paid out $40 million, the remainder of his contract.

Fox is unlikely to take a big beating financially from O'Reilly's departure.

Investors seemed to take the news in stride. Shares of Twenty-First Century Fox were down less than 1 percent at $30.50 in Wednesday afternoon trading.

O’Reilly’s departure will not have any effect on Twenty-First Century Fox’s overall profitability, said Brian Wieser, an analyst at Pivotal Research.
...“They could literally go dark during the time his program airs and they would still be profitable,” said Wieser.

As to who will replace him, according to New York Magazine, Fox wants a new host in place by Monday:

Fox News sources tell me that Tucker Carlson will be taking over the 8 p.m. slot and The Five will move to 9 p.m., effective Monday.)

The Five is the unwatchable show ever, in my opinion. It sometimes comes on Sirius when I'm in the car, and never listen more than 30 seconds. I can't stand the constant talking over people, loud laughing, and pointless chatter. It's like a bad coffee klatch. Maybe on TV it comes across differently, but I doubt it.