Jimmy Kimmel (Randy Holmes/AP)

In announcing that it would give Jimmy Kimmel the plum late-night time slot for which he’s been patiently waiting about a decade, ABC set up one of those Great Circle of Life stories to which its parent company, Disney, is so addicted.

In this version, NBC’s Jay Leno and CBS’s Dave Letterman are the old lion kings of late-night talk TV who are losing their grip on the kingdom. NBC’s Jimmy Fallon is Simba — maybe CBS’s Craig Ferguson is, too, although the press doesn’t seem to think so, which might say more about the press than it does about Ferguson.

And Kimmel, who has waited around for a chance at the 11:35 p.m. throne longer than those other two squirts — he celebrates his 10th anniversary with ABC late night in January — he’s Scar.

Letterman and Leno have both had great runs, Letterman as host of CBS’s “Late Show” since ’93, and Leno as host of NBC’s iconic “Tonight Show” since ’92 (with a brief timeout in late ’09 and early ’10, when Conan O’Brien tried, and failed, to dethrone him.

(Ironically, ABC made plays for both guys — Letterman in 2002, a plan that got scuttled when word broke out that the network had approached Letterman about replacing respected newsman Ted Koppel and his iconic news mag “Nightline,” and much media outrage erupted. And Leno in ’08, when he was being stripped of “The Tonight Show” so that NBC could hang on to Conan, and ABC offered him a home, only Leno decided to wait it out at NBC, which paid off.)

Now it’s 2012, and both Letterman and Leno’s late-night shows are tired, ratings-wise. This season, to date, Letterman’s averaging 3 million viewers, and Leno 3.8 million — millions fewer than they were less than a decade ago.

Both men are finishing behind ABC’s “Nightline,” although that three-decade-old news mag is also clocking far fewer viewers than it did less than a decade back.

Even so, it looks as though both guys will get to leave on their own terms. Letterman recently signed for two more years at CBS. And NBC is not expected to make a move before Leno’s contract comes up in fall 2013, while the network continues to lick its wounds over its botched effort to replace Leno with the younger, hipper O’Brien — who wound up being too young and too hip for flyover country. (NBC parent Comcast did, however, slash 20 of Leno’s staffers this month, and Leno agreed to take a pay cut to keep Comcast from slashing any more.)

So, this week, ABC announced that it was making a calculated gamble and giving Kimmel — who recently celebrated a July sweep ratings performance up 14 percent compared with July ’11 — the 11:35 p.m. time slot, starting in January.

This presumably gives Kimmel, 44, about two years to get settled at 11:35 — against the sexagenarians — before the younger crop of hosts moves in at NBC and CBS.

ABC clearly has been grooming Kimmel for some time, with all those prime-time specials, specials tied to sports broadcasts and plans to have him host ABC’s upcoming broadcast of the Primetime Emmy Awards.

This week’s announcement goes a long way toward explaining why ABC, which broadcasts the annual Academy Awards ceremony, recently expressed its unhappiness over the film academy’s interest in having Fallon host next season’s Oscarcast, a reaction that scuttled a deal. That trophy show will air within weeks, if not days, of Kimmel’s debut in his earlier late-night time slot, which ABC said in its announcement would happen sometime in January.

Kimmel’s audience is smaller than “Nightline’s” overall, as well as among the 18-to-49-year-olds who are the currency of entertainment programming. But ABC suits say advertisers are willing to pay a higher rate for a Kimmel-hosted entertainment show in the earlier time slot. Consulting firm Kantar Media told the Los Angeles Times the same thing, claiming last year that the half-hour “Nightline” took in $40.2 million, whereas Kimmel’s one-hour late night show, laboring in the post-midnight time slot, took in almost $100 million — up from the previous year’s $82 million.

Still, the move to the earlier time slot is not a ratings-growth slam-dunk for Kimmel.His show aired after late night’s No. 1 show for three consecutive years. Yet in the second half-hour of Letterman and Leno’s shows, during which they compete with Kimmel head to head, Kimmel does not win.

And over the past several seasons, we’ve seen that it can go either way when you take a show and give it a potential new, broader audience.

You can end up with “Big Bang Theory” moved to Thursday night and becoming the country’s No. 1-rated comedy — or you can wind up with Conan O’Brien moved up to “The Tonight Show” and becoming that season’s No. 1 failure story.