Few investments have paid off as handsomely in recent years as real estate in the world’s most economically vibrant cities like New York and London.

Real estate is a product that has natural limits on the growth of supply, while demand for assets that pay decent yields has skyrocketed. But even the world’s most canny real estate investors, like billionaires Sam Zell and Thomas Barrack, see potential pitfalls for the global real estate industry in the years ahead.

Barrack, for instance, believes that effects of disruptive technologies like Airbnb have yet to truly be felt by large owners of real estate like hotel chains. At a panel discussion Tuesday at the Milken Institute Global Conference, Barrack argued that companies like Airbnb will affect hospitality in a big way:

[Airbnb] is killing [the hospitality industry], of course. If you look at the hospitality industry . . . you have to adapt the regulatory environment, the tax environment, all of the local handicap requirements . . . keeping full-time employees. You just impute that on capital structure, versus a non-asset intensive engine of management, you can’t compete.”

Barrack doesn’t see regulators subjecting Airbnb, or those who rent their homes and apartments using the platform, to the same sort of regulatory requirements that hospitality firms face. He sees a wave of consolidation hitting the hospitality industry and that eventually, “you’re going to see a hotel manager merge with Airbnb.”

This analysis runs contrary to what the big hotel chains are saying. As Arne Sorenson, CEO of Marriott International, recently told the trade publication Hotel Management, “2014 was one of the best years of all time, a year that I’d love to bottle and open on New Year’s morning every year.”

Despite the fact that venture capital investors are valuing Airbnb at $20 billion, close to Marriot’s own market capitalization, the industry has generally argued that Airbnb is catering to a different market than those of traditional hoteliers.

Meanwhile, technology will affect more than hotels, Barrack says. He argues that commercial real estate has yet to feel the effects of technology that enables more telecommuting, reducing the need for office space. “Everything is being disintermediated,” he says. “Do we really need more office buildings?”

For Sam Zell, the biggest risk to big owners of property is the coming demographic transformation of the wealthy world. “This is the worst demographic situation we’ve had in 500 years,” Zell says. He cited estimates that Japan’s population will be cut in half by low birthrates by 2050, and argued that real estate investors may struggle to fill the buildings they own as population growth continues to slow in the developed world.