And now, here’s … Dennis, Whoopi, Rush and Jane. With talk-show maestro Johnny Carson about to pass the torch to Jay Leno next May, the line of late-night wanna-bes is growing longer than a Carson monologue on a bad night. By next fall, a half dozen talkfests–from an interview show with Whoopi Goldberg to TV commentary by radio reactionary Rush Limbaugh–could be served up to late-night viewers. “The Tonight Show” also faces new challenges from nontalk ventures, ranging from CBS’s “Crime Time After Prime Time” to “Studs,” a “Dating Game” knockoff. Not all the new entries will be around long, of course: overnight ratings are now available to half of America’s TV stations, and the instant feedback gives programs little time to find an audience. MCA and Fox canceled their low-rated “Ron Reagan Show” in November after just 13 weeks. Yet “Tonight’s” competitors insist the opportunities have never been greater. “They’re changing the executive producer and the band. They’re getting rid of [Ed McMahon]. They’re talking about a hipper format,” says Michael King, president of King World, distributor of “Wheel of Fortune.” “It’s a dramatic transition.” In one significant break from tradition, Leno said last week he’d replace Doc Severinsen with saxophonist Branford Marsalis.

Until recently, “Tonight” ruled latenight entertainment unchallenged. But the competition grew more serious with “The Arsenio Hall Show,” which premiered in syndication in January 1989. “Arsenio showed there was a whole audience available who didn’t like Carson, or who hadn’t watched late-night TV before,” says Betsy Frank, Saatchi & Saatchi Advertising’s director of new media. Arsenio also proved that low-cost, late-night programming could make big money: advertisers pay a premium to reach late-night viewers, predominantly working people between the ages of 18 and 34. Paramount, which distributes Arsenio Hall, has charged $20,000 to $25,000 for a 30-second commercial, which translates into profits of $62.4 million a year. NBC’s “Tonight Show” receives as much as $35,000 a spot-and takes in $100 million a year.

Despite continued high profits, the king is beginning to look vulnerable. According to the Nielsen ratings, “Tonight’s” audience has dropped by 600,000 households in two years. Carson now performs three nights a week, 37 weeks a year; the ratings stay the same when Leno fills in. (Upstart Arsenio Hall has lost 590,000 homes since 1989-90.) While NBC affiliates still recognize that “Tonight” is a valuable franchise, they have shown growing independence; last spring they pressured the network, over Carson’s objections, to delay “Tonight” five minutes each night so they could add more local news-and commercials. Some affiliates suggest Leno’s ascension could make them more willing to delay “Tonight” a full half hour. “Stations are finding out they can do as well programming a time period themselves,” says Brian Hocker, program director for the NBC affiliate in Dallas. Leno brushes aside the controversy with typical humor. Last month he told the “Tonight” audience that the five-minute NBC delay “was done to give Mario Cuomo a little extra time to decide if he wants to watch the show or not.”

For now, syndicators are targeting the affiliates of NBC’s rival networks, which are much more open to changing their late-night schedules. CBS has had some success with “Crime Time After Prime Time,” a series of action adventures. Even so, some CBS affiliates aren’t carrying the show, and others are delaying it. ABC has never found a suitable program to follow its successful “Nightline,” which frequently draws higher ratings than “Tonight” on big news days. In November the network canceled “Into the Night,” a low-rated comedy-talk show. Phil Beuth, ABC’s president of late-night entertainment, says, “We’ll come back when the climate is better.” But J. Philip Oldham, executive vice president of syndicator Genesis, doesn’t buy it: “When you give time to the affiliates it’s like pulling teeth to get it back.”

That’s just what syndicators are banking on. After ABC canceled its post-Koppel show, Tribune Entertainment, which distributes “The Dennis Miller Show,” began targeting ABC’s affiliates. Many were looking to fill the hole in their schedules. Miller stresses his differences from Jay and Arsenio. “I’ll be harder politically,” he says. Although all are aiming their shows at young viewers, Miller dismisses talk of demographics. “It comes down to: can they watch you five nights a week and not want to punch you?” Some 20 ABC stations, including such major markets as Miami and Detroit, will carry the Miller show.

Whoopi Goldberg is also hoping to profit from the instability. Her distributor, Genesis, says “The Whoopi Goldberg Show” has locked up 15 of the top 25 markets, including some ABC and CBS affiliates. Goldberg says her half-hour show will offer comedy plus interviews with showbiz celebrities and heavies such as L.A. Police Chief Daryl Gates. A tougher sell is Warner’s “Nightalk with Jane Whitney,” starring a former NBC Central America reporter described by Warner as “Oprah Winfrey with a hard-news background.” Warner hopes to launch the one-hour program in March in a handful of major stations, then expand if demand grows.

More late-night time slots may soon be up for grabs. Rumors continue to rumble that David Letterman remains bitter over NBC’s passing him up as “Tonight’s” host and selling his reruns to the Arts and Entertainment network without consulting him. If he leaves when his contract expires in April 1993, the move would throw late night into complete disarray. Eric Bremner, chairman of the NBC affiliate board, says Letterman was “shaken,” but insists he’s not going anywhere. Letterman has refused to comment on reports of his unhappiness. Meanwhile, late-night syndicators are looking west. This fall network affiliates in Sacramento and San Francisco shifted prime-time programs one hour earlier to 7 o’clock. The local news now ends at 10:30, opening 90 minutes of premidnight programming. If the trend catches on across the country, stations will be desperate to find more shows to fill the time. Who knows? Even late-night washouts may find their careers revitalized. Anyone talked to Pat Sajak lately?

With Johnny, Ed and Doc leaving “Tonight” next May, upstarts are climbing into the ring. Some have already landed on the ropes. ..CN.-TKOs

Host of ABC’s “Into the Night” was replace in July after a year. The latenight comedy-talk program died four months later.

Former First Son won respect as host of issues-oriented talk show, but dismal ratings doomed him after 13 weeks. ..CN.-Contenders

“Saturday Night Live” comic announce( his new show the same day Johnny Carson said he was retiring. Was it karma?

Former NBC Central America correspondent and TV host gets her own Oprah-style talk show, distributed by Warner.

Comic and movie star plans interviews with likes of General Schwarzkopf. Operation Whoopi begins next fall.

Right-wing radio host will interview guests, review movies, offer political commentary in new show from Multimedia.