Sirius Satellite Radio is placing a $100 million a year bet on the notion that the sophomoric humor and outrageous antics of Howard Stern will play in pay; his former boss, Infinity Broadcast, is banking on a batch of relatively unknown talent and new talk formats to make up for the loss of the shock jock.

The changeover is almost as seismic for radio as the changing of the guard in primetime newscasts is for the Big Three TV networks.

Whatever else one might say about Stern — and I’m with those who can’t abide his coarseness but who defend his rights of free speech — he has effectively rattled, roiled and regaled morning-drive listeners as potently as a strong cup of java.

Puritans, pundits and the politically correct have had to take cover for 20 years from Stern’s sturm und drang.

So too have others. Infinity has had to fork over several million in fines to the FCC for some of Stern’s more out-there assaults on the pieties, and a number of squeaky-clean advertisers have studiedly shunned the show.

Nonetheless, it’s been a cash cow for the network ($100 million in revs per annum) — something that obviously impressed former Infinity boss Mel Karmazin, who made hiring Stern away one of his first orders of business when he got the top gig at Sirius.

Meanwhile, the take-up of Sirius subscriptions is growing faster at retail chains than those of its rival XM, though both payboxes are still racking up quarterly losses. Sirius now has 2.2 million subs, XM 5 million.

Stern, who boasts about 6 million listeners on commercial radio, will take his wacko act to Sirius in January; his last Infinity Broadcast is skedded for Dec. 16. Meanwhile, Infinity is regionalizing his replacements on its 27 stations around the country, putting ex-Van Halen rocker-turned emergency medical technician David Lee Roth into East Coast markets, including New York. (The K-Rock format will de-emphasize music and become mostly talk.); irreverent TLC/Comedy Central comic Adam Carolla gets the West Coast gig, and various others, like Cleveland morning host Shane French, divvy up the rest.

In the radio realm, stars are not created overnight, so it could be awhile before listeners and advertisers take to Infinity’s new gameplan. And gabbers on other networks are sure to sharpen their own acts in hopes of enticing listeners abandoned by the self-proclaimed King of All Media. Gabbing, especially about the changing political scene, should make for big bucks in the next couple of years.

On the other hand, Stern’s schtick (presumably even more unfettered on pay radio), is not a sure-fire hit, either, and those fickle male listeners may just migrate elsewhere — especially if Stern’s bite no longer seems so delicious without obvious antagonists like the FCC or craven corporate bosses to chomp down on.

Who wins out in this expensive gamble will say a lot about the future of commercial and pay radio as well as about the changing tastes of American listeners.

Follow @Variety on Twitter for breaking news, reviews and more