With the latest wave of return-to-office delays from Covid-19, some companies are considering a new possibility: Offices may be closed for nearly two years.

That is raising concerns among executives that the longer people stay at home, the harder or more disruptive it could be to eventually bring them back.

Many employees developed new routines during the pandemic, swapping commuting for exercise or blocking hours for uninterrupted work. Even staffers who once bristled at doing their jobs outside of an office have come to embrace the flexibility and productivity of at-home life over the past 18 months, many say. Surveys have shown that enthusiasm for remote work has only increased as the pandemic has stretched on.

Apple has told corporate employees that its planned return to U.S. offices would be delayed until at least January. The Apple Park campus in Cupertino, Calif.

Photo: Sam Hall/Bloomberg News

“If you have a little blip, people go back to the old way. Well, this ain’t a blip,” said Pat Gelsinger, chief executive officer of Intel Corp. , whose company has benefited from the work-from-home boom. He predicts hybrid and remote work will remain the norm for months and years to come. “There is no going back.”

Return dates have been postponed repeatedly. On Thursday, Apple Inc. told corporate employees that its planned return to U.S. offices would be delayed until at least January. Companies such as Chevron Corp. and Wells Fargo & Co. have postponed September returns, while tech companies such as Amazon.com Inc. and Facebook Inc. have pushed them to early next year. Lyft Inc. said it would call employees back to its San Francisco headquarters in February, about 23 months after the ride-sharing company first closed its offices.

“ ‘If you have a little blip, people go back to the old way. Well, this ain’t a blip.’ ”

— Pat Gelsinger, Intel CEO

Prudential Financial Inc. delayed its office reopening from September to October at the earliest, though Rob Falzon, vice chair of the company, said that date could change, too, depending on health conditions.

Prudential plans to allow for a mix of in-person and remote work once U.S. offices reopen. But the longer people stay at home, the more Mr. Falzon worries about employees feeling disconnected. “My single greatest concern is around talent,” he said. “As individuals disassociate themselves with their organizations from a cultural standpoint, it becomes increasingly easy for them to make decisions to leave and go elsewhere.”

Already, many employees are “bombarded” with messages from recruiters and friends, attempting to lure them elsewhere, he said. “When they’re in the workplace, I think they have a broader sense of connection to the platform, to the culture of the organization—their fellow employees, their teams—that makes them less inclined to want to leave,” Mr. Falzon said.

Prudential Financial delayed its office reopening from September to October at the earliest, depending on health conditions. The company’s tower in Newark, N.J.

Photo: Victor J. Blue/Bloomberg News

Even so, what many have concluded over time is that their companies can operate largely effectively while remote, executives and workers say. After months spent hunched over kitchen tables, some employees say they have settled into a more comfortable rhythm of remote work. Others have finally sprung for more ergonomic desks or chairs at home. As more time passes until offices reopen, it could become difficult to convince existing employees to willingly upend their new lives and return to pre-pandemic schedules in offices, executives say.

Perceptions of remote work have shifted as the pandemic has gone on. When professional-services giant PricewaterhouseCoopers LLP surveyed employers across the U.S. in June 2020, 73% of respondents said they deemed remote work successful. By January 2021, when PwC released updated data, that figure rose to 83%. Now, more workers also say they want to stay at home full time. In new data released by PwC on Thursday, 41% of workers said they wished to remain fully remote, up from 29% in the January survey.

Some employers, including Gusto, a payroll, benefits and human-resources technology company, say they have reduced any anxiety about office reopenings by providing assurances that employees will be able to largely select how they work—and change their minds over time.

Lunchtime in Manhattan is less busy this summer.

Photo: Gabby Jones for The Wall Street Journal

The company earlier this year allowed most employees to select what it calls a work “persona.” Those who want flexibility could commit to using an office two to three days a week, with the freedom to work from home the rest of the time. Others could ask to stay fully remote. Roughly 64% of the company’s more than 1,400 employees chose flexible schedules, while 35% decided to go remote. A small number of employees, such as those who work in facilities or security, will need to be in offices full time.

Danielle Brown, the company’s chief people officer, said employees will be able to change their work style, and she foresees a process similar to that used during annual enrollment, when employees decide on benefits for the coming year.

Because it was made clear that employees weren’t locked into a choice, many felt a sense of relief and empowerment, Ms. Brown said.

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The prospect of two years out of the office still concerns many employers, though, if only because it is harder to get a sense for how employees are feeling now. Conning, a Hartford, Conn.-based institutional asset-management firm, recently told U.S. employees that they won’t be required back in offices, even on a hybrid schedule, until January at the earliest.

Chief Executive Woody Bradford said the company will be increasing training for managers over the coming months and encouraging them to communicate more with employees, setting up informal outdoor lunches and dinners, when possible, to help create a sense of connection.

“I think that’s going to be really important so people don’t feel like they’re just locked in their basements,” Mr. Bradford said.

Mr. Bradford said he has heard from some employees that they are happy with their new routines and reluctant to give them up, even a few days a week.

“There are people who have been working from home for, like all of us, a long time, and say that because it’s habitual, we’re used to it, and change is difficult,” Mr. Bradford said.

He is sympathetic to those arguments, but also tells employees that they must think of the organization as a whole. “An individual may be very productive at home, but the new employee who is trying to learn the culture and trying to develop through apprenticeship may really suffer too much,” he said.

Plexiglass dividers and floor decals might not be permanent, but the pandemic will bring lasting change to offices. Experts from the architecture and real-estate industries share how they are getting back to work and what offices will look like in the future. Photo: Cesare Salerno for The Wall Street Journal The Wall Street Journal Interactive Edition

Employers have tried a variety of tactics to ease the transition back into offices. Some, like law firm Schwabe, Williamson & Wyatt PC, based in Portland, Ore., have held soft reopenings, giving workers a chance to get accustomed to commuting, wearing dress clothes and interacting with colleagues in person again. “It takes a lot longer” to prepare for work than many may remember, said Graciela Gomez Cowger, the firm’s CEO. “You’re out of practice. Just putting on a good shirt and getting dressed is a thing.”

Others have provided detailed descriptions of the new office environment and protocols to try to ease concerns. State-owned Abu Dhabi National Oil Co. began bringing employees back into its offices in the United Arab Emirates last summer. The company found that many employees initially were uncertain and anxious about what awaited them in offices, said Coni Judge, a senior adviser for culture and employee engagement.

Company leaders attempted to demystify the corporate environment through messages, graphics and animations explaining new safety protocols. The company held town hall sessions before and after return dates to hear concerns and to answer questions. It focused on both the length and color of messages sent to employees. “People are in different psychological and physical states, and it’s important to recognize that,” Dr. Judge said.

Many workers are still eager to see offices repopulated, said Ms. Cowger, the CEO of the law firm Schwabe, which employs about 400 people across the Pacific Northwest. Her firm delayed its mandatory office return until at least November, though Ms. Cowger said she eventually wants employees back in offices, some of the time, to help local cities recover economically and to ensure colleagues learn from each other.

“We can’t keep our office closed indefinitely,” she said. “We just can’t.”

Write to Chip Cutter at chip.cutter@wsj.com