Hackensack, N.J. ? Don’t say we didn’t warn you: At some point in the next decade, there will be a “devastating attack” on the Internet or power grid.

That scenario was deemed most plausible by 1,300 technology experts and scholars in a survey released Sunday by the Pew Internet & American Life Project. Other predictions that drew the most agreement:

• People will be watched more closely by government and businesses through computing devices embedded in clothes, appliances, cars and phones.
• Most students will spend part of their day in “virtual classes,” grouped online with others who share their abilities.
• And the boundaries between work and leisure will be blurred — in other words, expect to hear from your boss anytime, anywhere.

Pew, along with Elon University in North Carolina, sought the opinions of people — both in the United States and abroad — who know the Internet intimately or think about it a lot. About half of them were Internet pioneers, having been online before 1993. One-third were from academia, another third were from tech companies or consulting firms, and the rest worked for nonprofit organizations, publications or the government.

Of the experts surveyed by Pew in the fall, 66 percent agreed that the Internet or power grid would be successfully attacked. Only 18 percent disagreed or challenged the prediction.

Former CIA Director Robert Gates, speaking at a terrorism conference last month, said cyberterrorism could be the most potent weapon of mass destruction and could cripple the U.S. economy.

“When a teenage hacker in the Philippines can wreak $10 billion in damage to the U.S. economy by implanting a virus, imagine what a sophisticated, well-funded effort to attack the computer base of our economy could accomplish,” he said.

Intensified surveillance by government or business, and more arrests as a result, was foreseen by 59 percent of the experts. Some said they would welcome that development; others seemed to dread it.

“There will be greater surveillance, probably; greater arrests, maybe. But this is a chilling prospect overall,” wrote J. Scott Marcus, the senior adviser for Internet technology at the Federal Communications Commission.