IF MIKE Nichols were to remake "The Graduate" today, "plastics" would not be the word of the future whispered into Benjamin's ear as he stands on the stairway in his parent's home.

The word would be "cable."

Just about everybody got into cable in 1981 except maybe Famous Amos and Lee A. Iacocca. CBS and ABC--of all people!!!--started their own hoity-toity cultural cable channels, prompting one West Coast wag to speculate that the networks were making regular television worse and worse so as to drive viewers into cable and thereby create a new industry for themselves.

Television has become something people get into only so that they can get out of it and into something else, and cable is proving to be, for now, the most seductive something else around. The depressing practical truth of the matter--at least from the viewpoint of one disgruntled subscriber to Arlington's tattered, battered and maddeningly quirky Metrocable service--is that there is no sign cable will prove to be better television, only that it will be more television.

Most of America still gets its television through the air while waiting for The Wire. What did America watch on TV in 1981 during those periods when there was no televised coverage of assassination attempts? The answer is, less than not-much. Broadcast television remains stubbornly stranded in a limbo, a lull between eras, as the technological changes click in and the roles of commercial networks, local stations, and public TV all face imminent and perhaps sweeping change as we move deeper into the wired thicket of the '80s.

The year's one triumph for network TV entertainment had to be the dark-horse victory of NBC's "Hill Street Blues," the only remotely original departure from prime-time programming formulas this year. "Hill Street" premiered in January and immediately became the darling of the critics--never a guarantee that a TV program is any good, by the way--and a so-what to the public. But after it garnered more gold statuettes than any show in history on the Emmy Awards in late summer, viewers finally began to realize it was on the air (and, in a precedent-shattering innovation for NBC, at the same day and time each week).

A considerably more remote outpost of inspired writing and glorious performance on NBC, "SCTV Comedy Network" returned in the fall, after a brief spring season, and proved as wily, imaginative, hilarious and cruel as ever. The repertory company, most of them recruited from the Canadian chapter of the Second City comedy club franchise, reigns as by far the merriest band in all of television, and they continue to take terribly therapeutic kicks and jabs at the rest of television in all its multifaceted and dauntless banality.

And yet late-night TV, which seemed a year ago to be entering a phase of experimentation--the original "Saturday Night Live" having staked it out as TV territory where originality and irreverence might flower--fizzled as the year wore on. CBS had more ratings success with a bloated soap, "Behind the Screen," than with any of the more ambitious pilot projects it aired in late night. Viewing levels were down, and though a revised "Saturday Night Live" constituted an enormous improvement over last year's notorious and abortive version, ratings for the program remained low.

As the year ended, Tom Snyder abdicated his late-night throne--he held the title of king and court jester simultaneously--and left the "Tomorrow" show. Late night, which once promised respite from, and antidote to, the calculated cacophony of prime time, was washing out. Some of those who had been developing projects for the period drifted away--into cable, among other things.

In news coverage, the year was dominated by the terrible--attempted assassinations of President Reagan and the pope, and the assassination of Egyptian President Anwar Sadat. Except for a flurry of overly hasty and sometimes erroneous reports during coverage of the Reagan shooting, and NBC's poor handling of the pope story (so botched that a Philadelphia affiliate dropped the network feed and covered the story on its own), these were again instances in which television as a technology proved itself an incomparable messenger.

And there were also elated moments, like the two landings of the space shuttle Columbia, the genuinely impressive pageantry of England's royal wedding, and the bizarre inaugural day spectacular that saw the networks cutting from the festivities in Washington to the release of the American hostages by Iran.

David Brinkley left NBC News for ABC News with mysterious suddenness, and Walter Cronkite finally turned over the baton of the "CBS Evening News" to Dan Rather, who was subject throughout the year to relentless scrutiny of his ratings, as if they were the body temperature of a patient in intensive care. Corporate diffidence about making too many changes in the look and feel of the "Evening News" (as if to pretend Cronkite had never left) proved extremely ill-advised, but by the year's end, with a new producer for the program and a new president of CBS News finally chosen, there were signs the "Evening News" could regain its dominance, though perhaps never again achieve the margin of victory enjoyed by Cronkite in his avuncular heyday.

CBS News suffered more substantial humiliations with "Morning," an essentially droopy attempt to compete with "Today" and "Good Morning America" (extensive remodeling was announced for the program at the end of the year) and "Up to the Minute," a perfunctory daytime informational series starring the not-so-indomitable four horsemen of "60 Minutes." The program got what it deserved: no audience, and the ax, in that order. Meanwhile, ABC News put Brinkley to work on a new program, "This Week," that sailed through a very brief shakedown cruise to become the best of the Sunday morning news interview shows.

But CBS News had the year's most impressive achievement in broadcast journalism, the five-part documentary series "Defense of the United States," produced by Howard Stringer's CBS Reports unit and in virtually every respect, a credit to television.

The Revs. Jerry Falwell and Donald Wildmon continued their tirades against television, but the movement seemed to be losing momentum. A threatened boycott of errant sponsors was abruptly called off, and Wildmon took the tack of declaring Christians a persecuted minority group (in the U.S.A.?) who are discriminated against by the big bad networks.

To offset the tedium and coarseness of everyday TV, there were productions and performances throughout the year that bolstered what faith in television remains--Peter O'Toole in ABC's fatally overlong "Masada," Alec Guinness in the sublimely atmospheric PBS import "Tinker, Tailor, Soldier, Spy," and, most recently, Sally Field's heartbreaking powerhouse turn in the NBC Live Theater production of Tad Mosel's "All the Way Home."

It's de rigueur to greet new years with grinny (and forgiving) optimism. What can be said in defense of 1981? Well, let's see: Fred Silverman left television in 1981; that ought to count for something. Yesterday's dynamo is tomorrow's footnote. As for cable, the year saw the introduction or announcement not only of culture channels, but also a pop music channel, a video game channel, an all-weather channel, additional all-news channels, and, inevitably, porn channels. Pessimism about cable's promise is offset by one overriding and inescapable conclusion: It's got to be better than what we have now.