THERE HAS BEEN plenty of wailing and shrieking in response to Johnny Carson's announced retirement from the "Tonight" show, much of it coming from the offices of NBC, which stands to lose millions if Mr. Carson is as good as his word. What the net loss will be for the rest of us, and for the state of television in general, is something else. There is no question that Mr. Carson will be missed. It is more than a case of a very talented comedican who has lasted 17 years (longer if you count "Do You Trust Your Wife?," the hilarious quiz show he presided over) in a high-risk medium. It is a case of Mr. Carson's having become television itself-a neat-as-a-pin, smooth-talking, sharp-dressing embodiment of all the vacuities and comforts the little box affords.

Yet, when you comd down to assessing those comforts and vacuities, they pretty much cancel out. On the one hand, Mr. Carson has provided something very special in the "Tonight" show-much more effectively than did Jack Paar, his flagrantly self-tormenting predecessor. He has not provided high political chitchat, or high art, or even high comedy, for that matter. But he did deliver what we have come to know as the classic talk show-a fast, colorful spray of noise and light, and a perpetual shuffling of the gabby famous. That was an accomplishment. If nothing else, it kept the world hopping after midnight.

On the other hand, he-also more than anyone-has created and promoted the idea of the professional personality; has in fact created it so successfully that no one who has followed Mr. Carson, along with his competitors, Merv Griffin, Dick Cavett, David Frost, can help wondering when the world will finally run out of professional personalities. This, of course, is immediately followed by the terrifying thought that we may never run dry, that Andy Warhol's prophecy about 15-minute universal fame will be realized on a screen before our eyes.

These two large gifts are what Mr. Carson will leave to television when he retires. And they are not the sort of gifts that disapper with the donor. Mr. Carson has pushed television to where it sits, unsatisfactorily, now-between populor pleasure and vast, insistent boredom. And the cause for wailing at his leaving the "Tonight" show may not be that he is irreplaceable, but rather that he is replaceable infinitely.