Twenty-one years ago, NBC announced an orderly transition for The Tonight Show, handing over the hosting reins from icon Johnny Carson to his permanent guest host, Jay Leno. Carson’s own favorite, Late Night host David Letterman, bolted to CBS.

In 2004, NBC vowed to do better, and announced an orderly transition for The Tonight Show — this time with five years notice for Leno to hand over the reins to Late Night host Conan O’Brien. And to prevent Leno from bolting, NBC chief Jeff Zucker put him in primetime. By early 2010, Zucker and NBC had a change of heart and tried to reverse course. Conan said no go, and bolted with millions of NBC’s money to TBS.

Now what?

NBC looks to announce an orderly transition once more for The Tonight Show.

After initial speculation reported in The Hollywood Reporter and The New York Daily News that NBC hoped to hand The Tonight Show to Late Night host Jimmy Fallon, Bill Carter of The New York Times — who wrote books about the past two times the Peacock Network screwed the pooch on this — reported Wednesday that not only was that happening, but in the coming 12 months and moving the late-night variety franchise back to New York City and 30 Rockefeller.

The more the other faces and names change, the more one thing stays the same: Leno in Burbank, winning the ratings at 11:35 p.m. among total viewers and ages 18-49.

What we also know for certain:

  • NBC recently extended Leno’s contract through September 2014.
  • NBC is building and renovating studios in 30 Rock in NYC, for Fallon.

Everything else is speculation.

File it all under circumstantial evidence.

Including Fallon’s non-denial brush-off at the top of his opening monologue Wednesday night, joking: “Before we get started, I have to talk about the rumors that came out today which say that I’ll be moving up to 11:30 or as my parents call it ‘umm, still too late.’ Actually the rumors are true. NBC is turning The Tonight Show into a diving competition. So exciting.”

Including Leno’s latest gag at his network’s expense. He has made a running joke of NBC’s failing ratings in primetime and finishing February sweeps in fifth place. On Wednesday night’s show, Leno quipped:  “According to several reports, scientists say they are getting closer and closer to being able to do Jurassic Park style cloning of extinct species. Imagine that? Things that were once thought to be extinct could bow be brought back from the dead. So there’s hope for NBC. It could turn around.”

Perhaps more telling, yet still only coincidental, was what happened Tuesday night on Fallon’s show with guest David Steinberg. The Roots welcomed Steinberg onstage with the theme to Carson’s Tonight Show, after which he and Fallon spent the first few minutes reminiscing about how they were in the same studio now that Carson was broadcasting from 50 years ago. Roll the clip.