It has been in the air for some time, but Apple can dodge the question no longer: How important is Steve Jobs to its future?

By all accounts, Jobs’ perfectionism, autocratic managerial style and disregard for conventional wisdom are at the heart of Apple’s remarkable streak of success.

Since he returned to Apple in 1996, the company has set a new standard for design in personal computers, built a chain of sleek and always-crowded stores, jump-started the sale of digital music and turned the mobile phone into a fun, flexible computer.

This is clearly the stuff of business legend. But now the company faces the real possibility that its inspirational leader may fade from the scene. Jobs, Apple’s co-founder and chief executive, said on Wednesday that he was taking a leave of absence from Apple until June because his health issues — he is a survivor of pancreatic cancer — are “more complicated” than he first thought.

That terse letter, after he had played down his illness just last week, left Apple watchers asking what might happen to the company if Jobs does not return in June as planned.

Analysts are quick to point out the strength of the company’s management bench. Timothy Cook, its longtime chief operating officer, will take over at least temporarily and is responsible for Apple’s manufacturing and sales operation, which are the envy of the consumer electronics industry. Jonathan Ive, Apple’s design chief, runs the team that has created much of the functional, visceral and emotional allure of Apple products, whose design ambitions extend right down to its elegant packaging.

But some Apple watchers and former employees are skeptical about Apple’s fate if it is forced to soldier on without Jobs.

“If you look at the history, Apple can coast for several years and still do very well,” said Paul Mercer, who worked for Apple in the ’80s and subsequently developed software that was used to design the user interface for the first iPod. “But it’s very risky, and without Steve, the long term is untenable.”

The stories about Jobs are well known, like his insistence that even the insides of the Macintosh computer, which hardly anyone ever sees, should look good. His obsession with detail permeates everything Apple does, and that principle will certainly not disappear from the company if he is gone.

But there are other aspects of his role that do not get as much attention and may be more difficult to replace. At many technology companies, various divisions often work at cross purposes, competing with one another to develop related products. This can lead to devices and software that are sometimes incompatible, frustrating customers.

Jobs, former Apple employees say, has the authority and long-term vision to yoke Apple managers and employees together under a single cause.

“Steve is terrific at attracting and retaining people, creating an agenda and getting people to stick to it,” said Stephen Perlman, a Silicon Valley entrepreneur who was a principal scientist at Apple in the 1980s. “It’s very hard to find somebody who is so credible, and who has such a strong following that he is able to cut through corporate politics.”

Jobs has also been Apple’s chief deal maker. After introducing the iTunes store in 2003, he persuaded entertainment companies to sell digital versions of their products when they were largely bivouacked, hiding in fear of piracy. In large part because of Jobs’ efforts, those barriers have fallen, though other challenges remain, like getting the Hollywood studios to relax their restrictions on renting or downloading movies over the Internet.

In their moments of great anxiety, Apple fans look back to the late ’80s and early ’90s for a glimpse of Apple without Jobs. After he was ousted in a boardroom coup in 1985, Apple actually thrived for several years, unveiling the first Mac with a color screen, the PowerBook laptop and QuickTime, which broke ground in bringing video to personal computers.

But then, to the horror of its die-hard fans, Apple withered. Its stock fell 68 percent from its 1991 peak to Jobs’ triumphant return in 1996.

In the meantime, three chief executives came and went, and Apple’s core product, the Macintosh, did not evolve as fast as computers based on Microsoft Windows.

Part of the problem, said people who were at Apple during the lean years, could be traced back to Jobs himself: He had not allowed anyone with talents similar to his own to rise at the company. Some think that may also be true today.

“Steve’s personality is such that he had not brought up other people who could do what he does. He’s the kind of person who pushes away people who are like himself,” said Ted Kaehler, who worked on the original team that developed the first graphical user interface at the research center known as Xerox Parc, and he later worked at Apple in the ’80s.

But some Apple watchers are reluctant to use the past as a guide. Andrew Hertzfeld, who helped develop the original Mac-intosh and now works at Google, says that Apple has had 12 more years under Jobs’ leadership to soak up his unique values.

He also notes that products already in the pipeline — which analysts say may include new iMacs and smaller iPhones — already bear Jobs’ imprint and can sustain Apple for years to come. “It will take half a decade for the absence of Steve to really show up in the products,” Hertzfeld said.

Some think Jobs’ imprint on Apple could last even longer, perhaps for decades, even if for some reason he is unable to come back this summer. James Breyer, an influential Silicon Valley venture capitalist, sits on the board of Wal-Mart and says the values of its founder, Sam Walton, still drive the retailer 17 years after his death.

“I can’t recall a board meeting where Sam’s spirit and contribution have not been cited in some way,” Breyer said. “In the same way, I expect Steve Jobs, through his genius, will always represent the DNA of Apple.”

After the initial shock of Jobs’ letter sent Apple’s stock sharply lower in after-hours trading Wednesday, investors were a little calmer Thursday. The shares fell 2.3 percent to $83.38.

Still, there are those who worry that Jobs’ absence will have an impact even beyond Apple.

“The whole world is concerned about Apple. I’m concerned about Silicon Valley,” said Perlman, the entrepreneur. “I need Apple to be harrying Microsoft. We need someone stirring the pot. God forbid that there is no one stirring the pot anymore. We’ll become Detroit.”