AMERICA WANTS to know: What is this the decade of? Why, it's the decade of All-This and All-That Television, of course. The number of new cable networks devoted to single kinds of programming is growing daily, but that isn't the half of it. It may not even be the eighth of it. It may not even be the merest smidgen of the tip of the immortal iceberg.

Imagining what's beneath such tips, and then insisting those imaginings are the absolute and indisputable truth, is what television criticism is all about.

Thus have we obtained through unnamed sources as confidential as ever there was a list of all the all-something cable networks on the drawing boards of the nation at this very moment. Of course, they might not all come to Fruition (that's Fruition, Ark., just wired for cable), they may not all uplink to the bird (technical talk--you wouldn't understand), and in fact, our sources, if they really exist, might be lying through their teeth.

AND YET--how surprised would any of us be, in this terribly confused modern world of ours in which we live in this day and age, to find out there really are such cable networks in the works as:

* Careen-o-rama, the 24-Hour Car Chase Network. Yes, now you can see the crash-ups, smash-ups, bash-ups and oopsy-daisies from "CHiPs," "The Dukes of Hazzard," and le cinema de Monsieur Burt Reynolds without having to sit through contrived plots, perfunctory character development and haw-haw comic relief. Uninterrupted footage of cars ramming and bamming, peeling and wheeling, sailing through the air, and landing on people's credenzas, all day every day from here to eternity. Also: selected abrasions and contusions.

* The Fatty Channel. Doctors have found that many people are fat. Scientists have found that many fat people eat like pigs. Doctors and scientists working together have found that for many chronic lardos, the major pleasure of eating is watching vast amounts of food disappear. So this channel offers a perpetual, pig's-eye view of a sumptuous banquet table, with hands reaching out from behind the lens, bringing food to the camera, and then making it disappear, as if it had been eaten! During prime time, the food devoured on camera consists of all the garbage being advertised at the same hour on the commercial networks. Viewers are warned in advance that though this revolutionary technique, Surrogate Eating, works for some dieters, others may find it drives them insane.

* The Channel Channel. Continuous reports on ship movements through the Panama Canal, the St. Lawrence Seaway and the Straits of Magellan. Viewers are lured with the channel's funsy slogan, "Isthmus Be the Place."

* Soccer from Romania. Now, at long last, a channel to turn to whenever your interest in life is at such a fever pitch that you simply can't imagine being bored. These soccer matches from a distant land--the only games of any kind not already being covered by some other cable network--will do the trick libpski-splibpski! Yes, it's the sport where hardly anything ever happens, and even if it did, you can barely make out the teeny-tiny players on the great big field to see it. Guaranteed to smother even the most resilient of high spirits.

* Barely Entertainment Tonight. All the latest press releases from Hollywood publicists and agents, read on the air 'round-the-clock by grinning mannequins disguised as human beings. The excitement and glamor that only news about nothing can have. As if that's not inadequacy enough, during the Zero Hour each night, there'll be in-depth interviews with such luminaries as John Davidson, Pia Zadora and Wayland Flowers and Madame, plus special sequences exploring the innermost thoughts of the Solid Gold Dancers. The perfect channel for all those people who get to the last hour of each year's Jerry Lewis Telethon and want still more of it.

* Orgazzo-vision. Cannot be described in a family newspaper.

* Angst-O-Matic. No home should be without one: a 24-hour channel devoted entirely to commercials for slicers, dicers, pincers, mincers, flickers, pickers, creamers, steamers, record racks, bamboo luggage, knives that last a million years and old Slim Whitman albums. Now you-you-you can see the commercials without having to sit through the old movies--or, better still, without having to watch Ted Turner's terrible Cable News Network. Operators are standing by. Major credit cards accepted. This offer will not be repeated (more than 100 times a day).

* Sports-Hype U.S.A. For the true aficionado, not to mention the true connoisseur, of sports: all the hype, none of the tripe. The interviews, the predictions, the pre-game analysis, the post-game analysis, the pre-analysis of the post-analysis, and endless prattle about odds and contenders by men in blazers, with no interruptions for actual events. Special feature: "Up Nose and Personal," penetrating profiles of goalies, linebackers, shortstops, punch-drunk palookas and the producers of beer commercials.

* The 24-Hour Nazi Network (a.k.a., Gestapo-Vision). America loves Nazis, in books, movies and TV shows, and now there's one convenient source for all your Nazi needs--from reruns of "Hogan's Heroes" to replays of every interminable Nazi mini-series ever made. There are Nazi fashions with your gracious, if demanding, hostesses Leni and Eva, "In Search of . . . Martin Borman" with Leonard Nimoy, and a new South American game show, "Guess My Real Name," hosted by Jack Narzi.

* Irving R. "Sweets" "Toots" Krellman's Cable Channel. Irving R. "Sweets" "Toots" Krellman, formerly known as Irving R. "Fats" "Toots" Krellman, occasionally known as Irving R. "Fats" "Toots" "Don't-Call-Me-Swifty" Krellman, started this cable channel for people who are sick to death already of cable channels. It's 24 hours a day of pitch-black silence, respite and sanctuary from HBO, CNN, ESPN and all that other junk. Wall Street analysts say this could be The channel of the '80s. Irving says, "You sick of television? Come on over to my place. Take off your shoes. Relax. Put your feet up. Look at nothing. You'll love it."