With the flight of opposition leader Joshua Nkomo to neighboring Botswana this week, the Zimbabwean government has prevailed in its increasingly harsh battle with the veteran nationalist leader and his party, at least for the short term.

The question remains, however, whether in the long run Prime Minister Robert Mugabe has made a much worse problem for himself by creating a permanently disaffected minority in Nkomo's tribal stronghold of Matabeleland.

Some fear that Nkomo's militant supporters, now loosely grouped, could form a guerrilla movement, seek support from South Africa and become a thorn in the side of Zimbabwe, as Jonas Savimbi's Pretoria-backed rebels are for the government of Angola.

For the time being, however, South Africa does not need to do anything, in the opinion of several NEWS ANALYSIS analysts, because Zimbabwe is effectively "destabilizing itself" with the tribal, political and personal animosity that has centered around Nkomo for the three years since blacks wrested power from whites in this southern African nation formerly known as Rhodesia.

Despite Nkomo's departure, the government maintained the pressure today, announcing the arrest of his wife, daughter and son-in-law, apparently as they were planning to leave the country. They are being questioned in connection with Nkomo's illegal departure.

In three days of roundups an estimated 1,700 people have been detained, according to official sources quoted by The Associated Press. Today, however, there was no sign in Bulawayo's vast black townships that the Ndebele masses who revered Nkomo were about to rise against the majority Shona tribe, which provides the basis for Mugabe's political support.

By fleeing, rather than staying to face possible arrest, Nkomo may have done Mugabe a favor. Rather than having to imprison the father of Zimbabwean nationalism and stage a long, divisive trial, Mugabe now faces the relatively minor disturbance of Nkomo's criticism from abroad.

"I think he will say a few things against Mugabe and then be quiet," a member of the Central Committee of Nkomo's Zimbabwe African People's Union (ZAPU) said. "The cards are heavily stacked against him."

"The only way he can start off something is to be exiled in South Africa. Unless Nkomo becomes a candidate for a mental institution, I don't think he will go to South Africa," said the party official, a critic of Nkomo who declined to be identified. "His absence might lead to people accepting a new situation within a few years in Matabeleland."

The key question is whether the former members of Nkomo's guerrilla army, who are blamed for the dissident violence in the southwestern part of the country, will be content with such a solution or will attempt to gain power militarily.

Sadly, the ZAPU politician said, there was no need for the current military confrontation, in which more than 1,000 civilians have been killed in violence by both the Army and the dissidents.

Many observers felt a great opportunity for peace was lost when Nkomo twice turned down the figurehead presidency after Mugabe won elections in 1980. In the view of optimists, that would have given Nkomo the prestige he desired as the veteran nationalist and at the same time would have paved the way for peacefully merging ZAPU into Mugabe's Zimbabwe African National Union Party (ZANU) as part of the prime minister's plan for a one-party state.

Whether that alone could have laid to rest a century of tribal hostility, two decades of political rivalry and wide personality differences between Mugabe and Nkomo is open to question.

Even though the two parties had a shaky alliance of convenience during the guerrilla war against white rule, they frequently fell out, culminating in Mugabe's decision to run separately in the 1980 elections, set up by the British-mediated negotiations at Lancaster House in London. With voting going along tribal lines, Mugabe won in a landslide.

"Dealing with ZANU, you can be sure there was never any time when we were together," Nkomo said in a recent interview. "We thought we were, at Lancaster House, 'til Robert decided to push off rather than discuss the situation."

Although Mugabe brought Nkomo into a coalition government, there was a steady erosion of relations. ZANU politicians attacked Nkomo, members of the two former guerrilla armies clashed twice around Bulawayo, Nkomo was demoted in the Cabinet and finally fired in February 1982 after the discovery of weapons caches on farms belonging to the party.

As a result, about 5,000 of Nkomo's former guerrillas deserted the Army. Many used their weapons to become common bandits, but several hundred became political dissidents seeking to use force to restore ZAPU's position.

From then on the two leaders' relationship was doomed, despite three meetings between Mugabe and Nkomo to try to work out differences and possibly merge their parties.

There was no way friendship could bridge the gap. It would be hard to imagine two national political leaders with more differences.

Mugabe is a small, controlled--some would say cold--intensely private person, who rules his party by consensus and whose intellect sometimes gets in the way of his political popularity. He often resembles an embarrassed professor as he raises his fists at political rallies. His precise, detailed speeches often lose his audiences, causing him sometimes to use wild rhetoric to retain the crowd.

Nkomo is unfailingly jolly, a man whose 300-pound bulk requires specially constructed chairs. He revels in political rallies, has ruled his party by personal fiat and is revered by his Ndebele followers. He often shoots from the hip and his failure to do his political homework has caused him trouble.

He made one of his worst blunders in late January. At a press conference, he accused the Army of slaughtering scores of his people in its offensive against the dissidents. He said that Josiah Gumede, former president in an interim government, had been killed by the troops.

Nkomo's information was incorrect. Mugabe, enraged because Nkomo had gone public with his charge without first consulting him, had Gumede come to Harare for a public appearance.

That allowed ZANU to deride all of Nkomo's claims, many of which were later substantiated by independent reports to the government that at least 1,000 civilians have been killed by the Army.

After that, sharp attacks on Nkomo and his party became regular features of parliamentary debate and press coverage as the government seemed to be preparing the public for his eventual arrest.

Instead, the man who was imprisoned for 10 years during white rule chose to flee. It was a move that certainly finishes a chapter in his long career and may well end his political significance.