In just 100 years, barring unforseen cataclysm such as collisions with out-of-orbit planets and other such bad-news events, we'll be celebrating our Trlcentennlal. More accurately, they'll be celebrating our Tricentennial, since most of us will be dusty memories, if we're lucky. There'll be a tidal wave of magazine articles and fancy picture essays written by heavy thinkers from places like the Hudson Institute, but I'm afraid when all is said and done, life as it will actually be lived In 2076 will bear little relationship to what we in 1976 imagine. Do you think for one split instant any fever-brained soothsayers of 1876 could have predicted the possibility of a Howard Cosell? Or that a few Arabs wearing Foster Grants would be in virtual control of the entire civilized world? Just to be sure, I looked up a reprint of a magazine article that appeared in July of 1876. The writer, a highly respected pundit of his time, predicted that "the year of 1976 will surely see the end of wars as we know them. Pestilence and disease will have disappeared, since science and technology will have rendered disease a rarity. Famine will be unknown, and man will have teamed to live in harmony . . . .'' I'm glad that poor geezer didn't live to see the Long Island Expressway at rush hour. . .