Most of my colleagues in the press appear to be treating Leonard Bernstein's announced retirement from the concert platform like an obit, but it is scarcely that. Not yet anyway.

To begin with, the purpose of last Tuesday's announcement was presumably to postpone an obit, at least for a while. At 72, Bernstein is in anything but the best of health, reportedly suffering from everything from progressive emphysema to a pleural tumor and respiratory infections. In recent months that has prompted him to cancel a number of engagements, including a tour with the Tanglewood Orchestra and a benefit concert for the Spoleto Festival in Charleston, S.C., in the wake of its devastation by Hurricane Hugo.What it does appear to write an end to is his conducting career, without a doubt the most extraordinary in American history. From the time he substituted at the last minute for an ailing Bruno Walter at a New York Philharmonic concert in 1943, he was clearly the man to watch, even at age 25. Fifteen years later he was made that orchestra's music director, and by the time he stepped down in 1969 had become this country's best-known conductor, maybe its best-known classical musician of any kind.

That was due in part not only to his work with the Philharmonic but his many TV appearances, his writing and his composing. Even there he carried on not so much the tradition of his European-trained mentors - Reiner, Mitropoulos and Koussevitzky - as that of George Gershwin, writing as many Broadway shows as he did symphonies. Many, I expect, will always first think of him as the composer of "West Side Story."

Indeed his departure from the Philharmonic in '69 was ostensibly to allow him more time to compose, but for the most part those projects came to naught. Within a year or two he had returned to the Philharmonic, albeit as a guest conductor. "This is my orchestra," he proclaimed to the audience, "and somehow I'm going to come back." At the same time he had already begun to expand his career overseas via telefilms and opera engagements, including a "Falstaff" and "Rosenkavalier" in Vienna.

There he was following in the footsteps of yet another composer-conductor, Gustav Mahler, whose music Bernstein did so much to promulgate. "I am Gustav Mahler," he once declared. But if that mirrored the Jeykll-and-Hyde nature of his professional life, it also hinted at the compulsion that lay beneath. Leonard Bernstein could no more stay away from the podium than he could avoid identifying with the composers in whose music he so passionately believed.

Mahler, of course, was a particular cause. But so were Ives, Copland and Nielsen, all of whom have had their international reputations enhanced via Bernstein performances.

By the same token the causes have frequently brought out the best in Bernstein. I'm not thinking so much of the fund-raising party he put on for the Black Panthers in the early '70s - an event that caused author Tom Wolfe to coin the term "radical chic" - as of his early advocacy of Marc Blitzstein, the "concerts for peace," his longstanding association with the Israel Philharmonic and, most recently, the Christmas Day celebration of the fall of the Berlin Wall.

Sure, the interpretations themselves have arguably become more indulgent, even a little crazy, over the years. I still remember hearing a Boston Symphony musician describe what it was like being cornered by Bernstein one evening at Tanglewood following a performance of the "Eroica" Symphony and having him go on about the historical panoply he saw unfolded in his mind while he conducted the "Marcia Funebre." But even in that Berlin Beethoven Ninth, in which certain things likewise seem to go on forever, the highs are genuine highs, possessed of an almost evangelical fervor. And on those occasions when it did all come together, the results could be unforgettable.

Significantly the last concert he conducted was also at Tanglewood, where he had earned his spurs 50 years before, a Koussevitzky memorial on Aug. 19 at which he not only had to stop at one point in the Beethoven Seventh but turned the baton over to an assistant for his own "Arias and Barcarolles."

Spokesmen say he will continue to write and compose, citing a new chamber piece and a musical-theater project that is to be completed next year. Maybe we'll see them and maybe we won't.

But I'm not at all sure we've seen the last of Bernstein the conductor. Already he has announced his intention to take part later this month in the Carnegie Hall AIDs benefit "Music for Life." By the same token, if medical problems don't do him in, I suspect somewhere down the road he may again be lured back by the event that's just too big to pass up, the cause that's just too good to resist.

That's what seems to have kept him moving as much as anything else in recent years. Surely apart from the musical possibilities it was the opportunity to make a statement that drew him to Berlin last December - witness his changing "Joy" to "Freedom" in the finale of the Beethoven Ninth - and to Prague this year for the first "free" Spring Festival since the Communist takeover.

We may not see him jumping 2 feet in the air anymore, but whatever he does you can be sure it won't be dispassionate. It is, after all, the combined physical and spiritual involvement of his conducting that have brought him to the top of his profession. Now they appear to have taken their toll, and I suspect he is entitled to a rest.

But should he change his mind, even for a one-shot, I'm sure we'll all be grateful. He's done it before, and we were then.