Conan O'Brien will take over the Tonight show next June—and what happens to deposed host Jay Leno after that is anybody's guess.

Leno's last show will be Friday, May 29, and O'Brien will start the following Monday, June 1, NBC executives told a Television Critics Association meeting on Monday.

NBC is angling to keep Leno with NBC Universal, but the late-night king has indicated he's ready to jump ship. Eager NBC competitors, including other networks and syndicators, are prepared to help him make the leap.

Ben Silverman and Marc Graboff, NBC Entertainment co-chairmen, were asked about the spectre of Leno being hired by ABC and overpowering O'Brien and top-rated Tonight.

"We really believe in the decisions we've made with our partners, including Jay," and stand by them, Silverman replied.

Graboff disagreed with the premise of the question, saying talks aimed at keeping Leno within NBC Universal post-Tonight are continuing.

But, Graboff added, "we've made our decision, we're happy with it, we're very confident the Tonight show will remain dominant in its time period."

Despite its prime-time woes, NBC has managed to maintain its late-night ratings dominance, although Craig Ferguson on CBS has challenged O’Brien lately. Now NBC is attempting a tricky transition based on a promise made nearly four years ago that O'Brien would succeed Leno.

The network attempted to defuse the issue on Monday with humour: Leno was seated among the press corps, disguised as a bald, bearded reporter who was armed with questions about himself.

But the exchange came off as more pointed than funny, unlike a similar staged encounter between ABC late-night host Jimmy Kimmel and a network executive last week at the critics' meeting.

Kimmel, identifying himself as a Florida newspaper reporter, tweaked his bosses as he posed questions about his job security if Leno comes to ABC; Leno, on the other hand, represents a threat to NBC if he goes elsewhere.

"[Green Bay Packers quarterback] Brett Favre retired and then wanted to come back," Leno said to Silverman and Graboff. "The Packers said no. What do you make of that?"

Favre retired in early March but recently expressed second thoughts about playing in 2008. The change of heart has drawn lukewarm enthusiasm from the Packers, who spent the off-season planning to move ahead with Aaron Rodgers as their starter—akin to the O'Brien-Leno switch.

"Everyone's entitled to change their mind. But I'd imagine that puts management in an impossible situation," Silverman replied, gamely.

"Is it true you've offered Leno a fifth hour on the Today show?" Leno said.

"That's a great idea, actually," Silverman said.

Nah, replied Leno, "It's a crappy idea."

Jimmy Fallon is poised to take over O'Brien's Late Night in March or April of 2009, after honing his approach in brief Internet shows, Silverman and Graboff said.

O'Brien will wrap his Late Night run sometime in the first quarter of the year, with exact dates to be determined, the executives said. O'Brien reruns will fill the gap until Fallon takes over.