Enter TV's newest sandman at 11:35 Tuesday night. Jimmy Kimmel himself is not so new, really -- though at 45 he's two decades younger than the other guys at that time. His show has also been on the air since January 2003. He is a known commodity, and has been for years.

But what makes this approaching moment in late-night TV history so new and bracing is simply this: A generational shift is about to take place that could anticipate, or very well force, changes on the other networks. Except for the brief and unfortunate detour on "Tonight" in 2009 -- Conan O'Brien (remember?) -- that hasn't happened in 20 years.

Late night -- for your purposes here defined as 11:35, or the house that Johnny Carson built -- moves more deliberately, more cautiously than any other time of day on TV. Dopey experiments or bad ideas are quickly rolled up (Chevy Chase), while those who succeed -- Jay Leno, David Letterman -- stay and stay. A nation turns its lonely eyes to them and not just for jokes, guests, pop culture, current affairs and politics, but for comfort -- and, after 20 years, Letterman and Leno are supremely comfortable presences.

But change is coming, and a successful challenge by Kimmel on ABC at 11:35 could hasten it. Letterman has already indicated that he is prepared to step down in 2014, when his current CBS contract ends. Leno has been beset by reports -- doubtless partly true -- that NBC is considering a succession plan in a couple of years as well, possibly moving Jimmy Fallon up an hour. Meanwhile, "Nightline" -- a reliable presence for 32 years, since the Iranian hostage crisis -- soon moves deeper into the night. Its future remains very much in doubt.

How will Kimmel do at 11:35? All indications so far seem to indicate that he'll do fine. As a talk-show host, he's self-aware without being self-conscious, ironic without being sarcastic, has more breadbasket appeal than Letterman -- and yet more urban appeal than Leno. He has none of Letterman's acerbity, or any of Leno's amiable factory-line functionality. He knows pop culture better than any of the other late- night hosts -- with the possible exception of Fallon -- and knows TV better than most TV executives.

As an interviewer, he's the equal of Letterman, and superior to everyone else because he has a journalist's instinct for the jugular, and for real news. He's genuinely interested in getting something newsworthy out of his guests -- even those guests (the cast of "Jersey Shore" last month) where there's nothing worth getting out.

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Starting Tuesday, he'll also bring his own road-tested bag of tricks, such as "Kimmel's Kartoons," funniest YouTube clips, Unfriending Friends on Facebook, and many others that are already popular with fans. (The extremely randy "Superfluous Bleeps from the FCC" may not come along for this new 11:35 ride, but that's not known for certain just yet.)

Asked -- as he always is -- during a phone call with a gaggle of reporters what changes he planned, he said: "I remember when I started doing the show, and people asked me what I was going to do and I had a lot of answers and almost none of those things turned out to be the case, because, just by experience and by figuring out what works, you wind up constantly changing your plan.

"There's this idea that you need to broaden the show or make it more wholesome or something like that. And I think that's a little bit out of date, that perception things have become so fragmented that you can continue doing the show that you've been doing."

For "Jimmy Kimmel Live!" -- the 11:35 edition -- that may be just good enough.