No disrespect intended to Megan Mullally and her recently canceled talkshow, but long before the “Will & Grace” co-star greeted a daytime audience, it was virtually impossible to find anybody who thought the exercise was going to work.This column seldom benefits from firsthand experience, so trust me when I say even hosting a weekly show on a little-seen cable channel is more arduous than it appears. And if history is any judge, nothing is more elusive — and in TV circles more valuable — than a talent who can successfully front an hour daily, whether that’s Regis Philbin in the morning or Oprah Winfrey and Dr. Phil McGraw in the afternoon or Jay Leno and David Letterman tucking us in at night. As a consequence, the road is littered with also-rans, many of them successes in other fields yet ill-equipped to sustain their own series, from Chevy Chase to Sharon Osbourne, Dennis Miller to Jane Pauley, Keenen Ivory Wayans to former NBA owner Pat Croce, Magic Johnson to Martin Short. Small wonder that a recent list of syndication’s most bankable stars devoted most of its top slots to hosts such as Winfrey, and that the soon-to-begin NATPE convention will be characterized by a lack of sizzle regarding new talk entries. Maybe execs are finally wising up to the fact that handing a talk franchise to a novice is like giving an 8-year-old keys to the Porsche and hoping he survives a midnight drive over the canyon. Of the commodities cited above, perhaps none is rarer than Philbin, who doesn’t do anything especially well on its face except inspire an audience to tune in day after day, almost without regard to who’s sitting next to or across from him. While there are serious ethical questions regarding human cloning, syndicators should press for a waiver to produce another Regis, if only to poke, prod and study the existing model beyond his inevitable retirement. Not surprisingly, as he cruises along, Philbin has noticed the pileup in the lane next to him. “If someone scores big in some arena, all of a sudden they give them a talkshow. It’s totally ludicrous,” he says. “I’m just amazed that these executives who like to call the shots are so quick to say, ‘He can do it. She can do it.’ ” Indeed, those who appreciate the talent and toil that goes into successful talk historically take umbrage at how cavalier studios have been in assuming actors or sketch-comedy players have the goods to make a go of it. Nor do most hosts with a gimmick — from psychic powers to self-help credentials — possess the breadth necessary to stay fresh from Labor Day launch until Thanksgiving. For Philbin, who drew inspiration from Jack Paar, the signs are unmistakable, suggesting “the daytime entertainment shows are practically extinct.” Although the era of hosts without a gimmick might have passed, it’s equally myopic to conclude that just having a hook, attitude or point of view is enough. Ultimately, the failure has been in taking the time to develop broadcasters in the old-fashioned sense. While names like Mike Douglas, Merv Griffin, Dick Cavett and Tom Snyder once fit that description, only Philbin, Letterman and perhaps Conan O’Brien hold up that mantle today — with the possible exception of Larry King and Bill Maher, the term “broadcaster” admittedly being a misnomer because they occupy the cable tier. Most other hosts, including Leno and Ellen DeGeneres, are gifted comics first and “hosts” second. Peter Lassally, who spent years producing “The Tonight Show Starring Johnny Carson” and is now an exec producer on Craig Ferguson’s “Late Late Show” for CBS, also puts his new charge in the “broadcaster” category. Beyond just a pretty face or sparkling personality, Lassally says, for a host to enjoy longevity, “There has to be a person there. … With Johnny, he was so well read he was just a thoroughly informed, well-rounded person.” Lassally echoes those sentiments about Letterman, and says of Philbin, “He’s a perfect example of someone who’s so good at it he makes it look easy.” Easy it is clearly not. Still, a hit talkshow offers such an enormous windfall that studios and station groups are to be forgiven for taking the plunge — the disclaimer being they’re doomed to more belly flops if they don’t look, and think, a little harder before they leap. So thanks for the time, Regis, and if it’s no trouble, would you mind sharing a few strands of DNA?