The strongest sign that the end of the age may be approaching is not the position of the planets against the sun, or that the sultan of Oman may someday have the bomb. Merely that civilization now has its first certifiable case of ESPN Divorce.

It came to light last week in Austin, Tex. John Kelso, a columnist for the Austin American-Statesman, told the story of a friend of his, a doorman at a local music club, who was divorced by his wife because he spent too much time sitting before the television, eating Mexican food and barbecue, and watching whatever was being shown on ESPN, the 24-hour cable sports network.

"I just watched ESPN all the time," the guy said, explaining why she snuffed him after 1 1/2 years. "I mean, all the time."

If the end does not come by earthquake, tidal wave or mushroom cloud, it probably will arrive via Professional Rodeo (taped) at 3:30 a.m. April 10, from Mesquite, Tex., or Full Contact Karate (taped) at 4 a.m. April 13 from Topeka. Of course, it also may draw nigh during the wall-to-wall NCAA tournament basketball games ESPN now is airing, some live in prime time.

The thing is that ESPN--like the drip-drip-drip of the water faucet--is always there. As one viewer told the network, "I watch your channel so much, if World War III broke out, I wouldn't know it unless you told me."

In the interest of marital harmony, it ought to be pointed out that the Washington area, outside Arlington, Gaithersburg and other widely separated pockets, doesn't have cable TV or ESPN. In other words, a few more years remain before the final days set in.

The District, for example, won't have cable until 1985 at the earliest (cynics say 1990-95 if the city takes as long to award a franchise as it does to collect its garbage). Target dates for full service in other jurisdictions: Montgomery County, 1985; Prince George's, 1984; Fairfax 1987.

Is the absence of ESPN here a blessing or a curse? You be the judge.

For the last two weeks, ESPN has been steaming through a 22-game schedule of NCAA games--all the first-round, second-round, and regional semifinal games CBS hasn't shown. If you miss a game or two live, fear not. Each game is replayed via tape delay. You probably can catch it at 5 a.m. after the Tiddlywinks playoff from Kuwait.

Take the North Carolina-Alabama game CBS will show via tape delay at 11:30 tonight. ESPN would have carried it live at 8, but CBS had first crack and thus could play keepaway. ESPN will sub with the Villanova-Memphis State game live at 7. It will be retransmitted at 4 a.m. Saturday morning, right after a live, half-hour news wrap-up called "Sports Center."

With ESPN reaching only 118,000 viewers in the "Washington" market, which extends as far as Hagerstown and Baltimore, there's a kind of cable junkie subculture now being born: Orgies of ESPN-watching at Arlington apartment houses. And in the best tradition of beer-drinking, barbecue-eating, spouse-neglecting viewing, ESPN games are picked off the satellite by a tavern named Poor Robert's on Connecticut Avenue.

The feeling here is that anyone who has seen ESPN has seen the future.

Owned lock, stock and minicamera by Getty Oil, ESPN (Entertainment and Sports Programming Network) still must answer a $64 question: Can a round-the-clock, pure-sports network survive while relying almost entirely on advertisers? Even Charles Van Doren would have trouble with this one, for the prestige sports still are controlled by the commercial networks and ESPN must eventually attract showcase events to prosper.

Nevertheless, the auguries are good.

ESPN now plays to 15 million homes nationwide--18 percent of the country's television households. Expanding at the rate of 500,000 homes a month, the network expects to be in 32 percent of all homes by the end of this year. By 1990, two out of three American homes should be cabled, meaning that Getty Oil will be dipping its mitts in whatever sits at the end of the rainbow.

Like George Allen, ABC believes the future is now.

Several months ago, it struck a tasty little deal with ESPN that may keep both networks ahead of their competition past the year 2000. ESPN gets unaired portions of ABC events (such as live, early-round action in the U.S. Open golf), and ABC gets the right to buy up to a 49 percent interest in ESPN in the future.

What's more, ABC and ESPN soon will announce the debut of a pay-cable system they will begin operating jointly this summer. The Larry Holmes-Gerry Cooney heavyweight title fight, currently scheduled for June, may well become the first event that ABC-TV and ESPN directly bill their viewers for.

Says ESPN President Chet Simmons, former top man at NBC Sports:

"I don't think all of a sport will be on pay cable. Not all of the NFL will be on pay cable (by 1988), but I think some of it will be. The revenue-generating potential is so overwhelming, it's just going to demand it."

Asked how poor folk will be able to watch, Simmons said the government might be able to underwrite the costs. Funny guy, this TV soothsayer, but his words were only half in jest. "You ever hear of 'cable stamps?' " he asked.