In the long haul, the Supreme Court's decision last Monday in the case of cable TV will not amount to a hill of beans - and given the headlong rush of technology, the long haul is likely to be a short haul. Within five to 10 years, Justice Anthony Kennedy's regrettable opinion won't matter.

For the time being, the 5-4 decision compels cable operators to carry the same programs carried by local over-the-air broadcast stations. That is all it amounts to.The "must carry" rule will assure that non-cable households - about 40 percent of all households - will continue to receive free programming. The decision supposedly will preserve "diversity" on the airwaves. Four members of the high court further contend that "must carry" will promote fair competition.

These are laudable objectives, but they will be attained at a price. Justice Kennedy's reasoning is wrong not only in economic principle but in constitutional principle also. The only good thing that may be said of the opinion is that it rests upon deference to legislative authority. In close cases the court rarely has anything kind to say about Congress. The novelty is refreshing.

The economic reasoning is to this effect: If cable operators are not compelled to carry local TV stations, the operators are likely to evict them from cable. Without the advertising revenues that result from cable access, the local stations could not afford "quality" programming. Their audience would fade away. Facing ruin, some stations might go into bankruptcy. The risk of financial difficulty is both serious and real.

Justice Kennedy said defensively that "must carry" is not intended to guarantee financial help for ALL broadcasters but rather "to ensure that a base number of broadcasters survive to provide service to non-cable house-holders."

What is this "base number"? Who is to decide which broadcasters survive and which ones fail? The loss of even a few stations, said Kennedy, "is a matter of critical importance."

Since when? Broadcasting is a business, just as newspapering is a business. The weak perish and the strong survive. Call it the law of the jungle if you please, but a metaphorical jungle is indeed out there. The survival of a vulnerable broadcaster is no business of the federal government. This is a function of the marketplace, of the age-old law of supply and demand.

To be sure, the power of the government to punish restraint of trade is well established. I would not argue for repeal of the antitrust laws. That is not the point. If local broadcasters offer a jerry-built product, why keep it standing? The guppy that can't swim goes belly up. Let me tell you sometime about the Washington Evening Star.

The constitutional principle bothered Justice Stephen Breyer a good deal. In a reluctant concurring opinion, he agreed that the court's decision interferes with the right of the cable operators to choose their own programming. Certain programs will have to be displaced to make room for those that now must be carried; the displaced programs will lose their audiences.

Moreover, Breyer conceded, the "must carry" rule will deprive some cable viewers of programs they would have preferred to watch. So much for "Cooking With Greens."

On the other hand, he said, there are compensations. By compelling cable operators to carry programs in Spanish or Chinese, or to offer home marketing, or to broadcast the sermon of a local minister, a "rich mix" of programming will be assured. Small stations will thus generate the extra dollars needed to stay alive.

The answer to that argument, again, is that a "rich mix" is simply none of the government's business. When we talk of "quality" programs and a "rich mix," we are talking of program content - and here the high court falls into the deep waters of First Amendment jurisprudence.

I know that historically the government has reserved the power to condition broadcast licenses on the degree of public service a station provides. That may have been a defensible idea a half-century ago. I'm not sure about that. I am sure that if a market exists for the proceedings of Congress or the sermons of some sawdust evangelist, the market eventually will be served.

Ah, well. Let it go. In every field of technology we are always driving a Model T. In a few years we will have five-inch dishes selling for $5, and these marvelous contraptions will bring us 500 voices from a thousand satellites. The mix will be rich - and indigestible too.