Cheers for Colbert’s ‘Late Show’ move, but which persona will emerge?

Like many Americans last week, I greeted the news of David Letterman’s retirement in 2015 with regretful acceptance. I love him with a love deep and true, but the man is pushing 70, and at least we could look forward to another year of his fine, cantankerous self.

But now I cannot wait for him to go. From the moment it was announced Thursday that Stephen Colbert would be taking over “Late Show,” I was ready to box up Letterman’s stuff and move it myself.

Because I have to know: Will Colbert change the nature of late night or will the bravest comedian on television just sell out?

No doubt the answer will fall somewhere in the middle, though it is difficult to imagine Colbert occupying any shade close to gray.

VIDEO: Stephen Colbert out of character

His Comedy Central show “The Colbert Report” is, after all, a straight-faced and deeply pointed send-up of the narcissism of talk shows, with all their thinly veiled ratings courtship and personal-brand worship. Playing a self-satisfied conservative pundit that seemed loosely based on Bill O’Reilly, Colbert is the sharpest, most overtly political popular comedian working today.

A true satirist in a world full of snark-flingers, he has an unapologetic preference for conservative targets but is willing to skewer anyone. Alone among his liberal brethren, he regularly talks up God while taking down organized religion including his own very public Catholicism.

The 49-year-old host teases celebrities and public figures way out of their comfort zone, and engages intellectuals in absurd conversations designed to expose the general ignorance of the American public. He and his writing team are so clever, so sophisticated in their humor that it literally took years for many viewers to understand that the self-aggrandizing, often self-contradicting conservative posturing was, you know, a joke.

Obviously, Colbert owes much to Letterman, who made sardonic de rigueur and eventually settled into the role of late-night’s cranky truth-teller in contrast to Leno’s part as sweet and affable uncle. And just as clear, CBS wants to continue, and indeed, sharpen that difference, especially as Leno’s replacement, Jimmy Fallon, is taking his guy-next-door charm to new heights on “The Tonight Show.”

PHOTOS: Stephen Colbert’s journey to ‘The Late Show’

But to have the Stephen Colbert we have come to know show up as the host of “Late Show” would be a bit like watching a spear-wielding scuba diver show up at the Vanity Fair Oscar party. Indeed, minutes after the news broke on Thursday, Colbert made it clear that he will not be hosting his new CBS show as the man the world has come to know as Stephen Colbert.

So who will be showing up at 11:30 on some as yet unspecified night in 2015?

Well, for one thing, a comedian whose boyish mien and youthful demographic belie his age (50, at the end of May), which is something of the holy grail these days. More important, Colbert is a geek with social skills, which puts him on the high-performance end of the rising matrix that now rules popular culture.

He hangs out with Cardinal Timothy Dolan and supports gay marriage, he drinks beer (on air) and speaks Elvish, has a penchant for referencing both classic literature and his genitals. Sometimes, in the same sentence.

So “smart is the new sexy” is now coming to late night. Where he may or may not wield a model of Glamdring and sit in his own replica of the Iron Throne.

Though always too busy being intentionally rude to be considered a real “host,” Colbert can also be an engaging interviewer. The guest appearances on “The Colbert Report” are of course part of the act — he regularly advises guests to treat him like the jerk who won’t shut up — but within that construct they are, more often than not, lively and informative. Although he often goes in with a clear purpose, and occasionally wanders too far off track, Colbert has an improviser’s talent for actually listening, something surprisingly rare in talk show hosts.

WATCH: Stephen Colbert’s memorable moments

Still, it’s difficult to imagine Colbert giving up his radical nuns and fascinating scientists to spend night after night chatting with ScarJo and other A-listers with movies to shill. More worrisome is how, or rather if, his political and religious humor and general comedic ruthlessness will play on CBS.

Though he, like Leno and Letterman, will no doubt deal with politics, he will have to soften his barbs and spread them around more, well, liberally. God only knows what he’ll do about his obsession with Pope Francis.

Then there’s the issue of the platform. Even if they chose Letterman over Leno, people traditionally tune in to the big late-night shows for a gentler experience than Colbert delivers on Comedy Central. Satire demands a high level of discomfort from its audience and Colbert is a comedian who does not blink, who believes that humor works best when it has something to say.

And much of what Stephen Colbert has said is very important.

Clearly he and his writers believe they can fashion a persona to fit both the “Late Show” form and function. As he has proved himself an intelligent and canny performer, it seems likely Colbert will succeed; the curiosity factor alone would seem to guarantee a strong opening.

But while there was nothing to mourn when Fallon stepped up to take over from Jay, or even when Letterman moved his show to CBS, Colbert’s ascension to the big leagues leaves a hole in television, and comedy, that will be all but impossible to fill. For all its adorable quirks and hilarious YouTube-able moments, “The Colbert Report” is one of the most politically and culturally important shows we’ve got.

So this new “Late Show” had better be worth it.

mary.mcnamara@latimes.com