Nearly everyone in this village set on a breezy plautea can tell you that at this time next year Southwest Africa will officially be called Namibia - as almost everyone but the South Africans have called it for years.

Hardly anyone, however, can tell you what that official change will mean.

"Uncertainly, that's the worst thing in Windhoek right now," said a municipal worker.

Will the change mean that this huge territory will continue as a virtual "frontier province" of South Africa, protected from guerrilla incursions by South African troops, and governed by a white-led coalition of ethnically based parties?

Or will it mean by a Marxist-oriented black movement called the Southwest African Peoples' Organization (SWAPO), a project which frightens the estimated 100,000 white "southwesters." If so, will SWAPO then offer young black South Africans bases for a guerrilla war against Pretoria?

While these and other less extreme variations on Namibia's future are pondered by residents of this territorial capital, a document worked out after a year of negotiations between South Africa and SWAPO will be presented to the U.N. Security Council for approval this week. It calls for U.N.-supervised elections on a one-man, one-vote basis for a constituent assembly. The assembly is to write a constitution for an independent Namibia.

The population of Windhoek, black and white, is skeptical that the plan will work and residents are plagued by mistrust, suspicion, violence and fears of the future.

The stakes are high. The size of Texas and Oklahoma together Nambia is big enough to give each of the 850,000 inhabitants more than a million square feet of land.

Beneath the semi-desert surface lies a wealth of minerals including uranium, copper and diamonds, and American companies like Bethlehem Steel and American Metals climax hold sizable mining interests. Mining is Namibia's principal ecnonomic activity.

For South Africa, the stakes are highest. To lose control of this territory, which it has administered under a League of Nations mandate since 1920, threatens preforia with a possible Soviet and Cuban presence only 350 miles north of its parliamentary capital in Capetown.

South Africa agreed under international pressure in 1975 to give Namibia independence, but most whites here doubt that Pretoria will freely give up its strategic advantage.

"If South Africa relinquishes its front-line strike bases, she's finished," said Hannes-Smith, editor of the Windhoek Advertiser, with a sweeping gesture toward northern Namibia on his wall map.

South Africa has about 20,000 troops stationed in Namibia to prevent infiltration by SWAPO's estimated 5,000 Cuban-aided guerrillas from neighboring Angola.

"We're almost there," said one South African critic referring to the near agreement between South Africa and SWAPO. "The question is, does South Africa intend to be there? A SWAPO win is in the cards, the (South African) dilemma is how to avoid the election," he said.

But the whites also perceive SWAPO reluctance to take part in elections. "That's my one political baffle," said Smtih, "because it is the party with the majority."

"As the Western proposals now stand, it means a SWAPO win," said a South African military official. Under the plan, South African troops are to be reduced to 1,500 men after a ceasefire in the guerrilla war, which dates back to 1966. A U.N. peackeeping force is to take their place.

"This withdrawal will be seen as a defeat for South Africa," theoffical explained, "because SWAPO has U.N. recognition as the sole representative of the people. . . . The people will naturally vote for whoever is seen to be stronger."

Other political observers here agree that SWAPO would either win a hefty plurality in the election or, at the very least, run neck-and-neck with the leading contender, the Democratic Turnhalle Alliance, a white-led coalition of political parties organized on tribal lines.

The alliance is led by Dirk Mudge, 50, a white farmer who broke last year from an offshoot of South Africa's ruling National Party to ally with moderate black leaders when he saw that the old party could not compromise enough on sharing power to elicit any black support at the polls.

Mudge claims to have 50 per cent of the whites behind him but some disgruntled "Southwesters," as whites born here call themselves, refer to him as a "communist" for breaking away from the National Party.

The alliance finds its support among the seven African tribes and two mixed-race communities who fear domination by the 395,000-strong Owambos, the largest ethnic group and the backbone of SWAPO support. The 100,000 whites are the second largest group.

Mudge has said that an Alliance government would ask South African troops to remain to defend it and the Alliance is unlikely to repeal segregation in housing and schools. Many whites predict that the Alliance will break up once the blacks realize they will not get equal rights in all areas.

The Alliance, which South Africa would like to see win power, has already begun its election campaign. At a political rally under a huge tent set up in the windy sheep-farming village of Karasburg, the message is that the Alliance "is the only multiracial group in Namibia" and that SWAPO is anti-white and communist.

For the mostly uneducated rural blacks at the meeting, this was vividly portrayed by a drawing on the platform portraying a church over which hung a sickle dripping blood and held by an arm labeled "SWAPO" and "kommunism."

The biggest guessing game in Windhoek is where the Alliance's money is coming from.Rumors mention West German foundations and financiers and South African and American mining interests. Mudge has denied some of the rumors but he is presently bidding to buy the only German- and English-language newspapers in town. He already has an Afrikaans paper. This would give the Alliance a press monopoly in this town of 80,000.

SWAPO people call Mudge's group the "disunited tribal alliance" disparaging it for its South African-style ethnically based politics and government-by-consensus, which, in practice, means a white veto over all decisions.

Although support of SWAPO is mainly among the Owambos, it appeals to the young in all ethnic groups who insist on a national consciousness. They blame the Alliance for a recent spate of political violence which left about 30 people dead. It climaxed in the assassination of Herero chief Clemens Kapuuo, the Alliance president, three weeks ago.

Enmity between the Alliance's Herero followers and SWAPO's Owambo supporters reached such intensity after Kapuuo's death that all top SWAPO officials fled Windhoek, fearing retribution from the Hereros who blame SWAPO for the chief's death. All Alliance leaders now travel with armed bodyguards.

"Everyone is very suspicious, especially the Owambos," said a young mixed-race taxi driver. "You say good evening to them and they stare at you. You have to do this," (give the clenched-fist power salute of SWAPO), "then they will speak to you. They say that Namibia is for blacks only."

Despite Cuban and Soviet backing for SWAPO no one here knows for sure how it would act in power - whether is would follow a hard ideological Marxist line such as in Angola or a more pragmatic, flexible socialism as in Mozambiquo.

Most whites do not believe the U.N. task force which is to come in under the proposals will be impartial. "How can you trust someone who has publicly called you a rogue so many times in the past?" asked one white. The U.N. representative, however, would work jointly with the South African-appointed administrator general now in charge.

Despite the uncertainty, the whites, 60 percent of whom are Afrikaans-speaking with close ties to South Africa, have not begun to leave, although some believe they will eventually.

"They say to me, 'I didn't know I was so liberal,' because they invite a black man into their office and give him a cup of tea. But they will all leave if they can," said a white businessman.

Others disagree. "I can tell you one thing. The whites here have made an oath to themselves that this will not be another Angola," said one city hall employe, referring to the mass exodus of 400,000 Portuguese from that former colony.

"The Portuguese were softies. But we Southwesters arren't. Almost everyone here knows how to use a gun."