The question of America's future president is at hand. But what about Ronald Reagan -- what does his future hold? Syndicated columnist Liz Smith informs her readers that the former actor can make a quick buck by reentering show biz at $1 million per Las Vegas act. Not too shabby.

Smith reports that producer George Schlatter, the creator of "Laugh-In," who booked Reagan in 1954 for the actor's first Las Vegas nightclub act, was in Las Vegas recently doing a 75th anniversary special for ABC when one big-time casino owner asked him if he could book the president when he leaves office. Schlatter, who at first thought the man was joking, responded, "No $25,000 a week this time. I won't talk to him unless he gets $1 million weekly. And that's the minimum." According to Schlatter, "the guy never blinked an eye and told me to go for it." Schlatter figures it's all academic until January 1989.

Jean Harris, Writing Again Jean Harris, who is serving a 15-years-to-life sentence for killing Scarsdale Diet author Dr. Herman Tarnower, says she is keeping her spirits up by working on a second book, entitled "They Always Call Us Ladies: Stories From Prison." Harris, 63, told the Stamford, Conn., Advocate that her book, the history of the Bedford Hills prison since its founding as a women's reformatory in 1901, is scheduled for publication in June by Charles Scribner's Sons.

Harris, author of the autobiographical "Stranger in Two Worlds," shot Tarnower to death in 1980, allegedly because he was going to leave her for a younger woman. She has maintained that she shot him while trying to kill herself.

Kasparov's Welcome Home World chess champion Gary Kasparov, now back in Moscow, says he is looking forward to three years of normal life after his 24-game title match against challenger Anatoly Karpov, the Soviet news agency Tass reported yesterday.

Kasparov, 24, was greeted on his return from Seville, Spain, on Monday evening by leading Soviet chess officials and crowds of Soviet fans.

Kasparov, who saved his title on Saturday through a spectacular comeback victory in the final game, will hold the title for three more years.

Kasparov said he planned to rest, recover his strength and work on new ideas before competing in two international grand prix tournaments and the Soviet national chess championship.

As for Saturday's final game, Kasparov said, it was a psychological test in which Karpov lost patience and failed to find an adequate defense.

Ralph Yarborough's Surgery Former senator Ralph Yarborough, 84, underwent heart surgery yesterday and was reported in stable condition, a hospital spokeswoman said.

Yarborough, who entered Seton Medical Center in Austin, Tex., Saturday after complaining of chest pains, underwent approximately three hours of surgery for aortic valve replacement and a quadruple bypass, said spokeswoman M.A. Bengston. His wife Opal and family were reported at the hospital.

Yarborough served in the U.S. Senate from 1957 to 1971 and is best remembered for his opposition to the Vietnam war and support for desegregation and social programs. He lost his Senate seat in 1970 to Sen. Lloyd Bentsen.

A Farewell to Yuppies It may be too good to be true, but a university professor predicts that yuppiedom -- the pursuit of fine living with no strings attached -- is on its way out. Tradition and family are slowly taking its place.

Charles Gross, a University of New Hampshire marketing professor, attributes the fading of the life style to October's stock market crash, AIDS and the process of aging. A former business consultant, Gross suggests that yuppies (young urban professionals), some now into their late thirties, are feeling their biological clocks ticking and want to have kids.

Another indication of the yuppie fade-out, says Gross, is the decline in applications to top business schools that specialize in finance. And female yuppies? "It's sort of a fashionable thing for highly educated women to leave their careers and focus on raising their children," he said. "People are choosing to lead a more traditional life style."