“Gated suburb” isn’t exactly what springs to mind when you think of New York and its hectic avenues, blinding lights, and incredible diversity. But Richard Florida, a professor at the University of Toronto who was once branded the world’s most influential thinker by MIT, says the Big Apple is “tipping” in the direction of becoming one.

The swaths of highly educated and creative people returning from the suburbs to cities like New York since 2000 has had conflicting effects, said Florida, whose 2002 bestseller, The Rise of the Creative Class, was a pioneering analysis of societies’ shifts away from a dependence on industry to “knowledge economies.”

Clustering all these intelligent go-getters together drives growth and dynamism, but also causes gentrification, which kills off diversity by pricing out the less economically fortunate. This problem is ingrained not just in New York, but a stack of “superstar” Western cities like London, Los Angeles, and San Francisco, Florida argued, at an Oct. 13 panel at New York University’s Schack Institute of Real Estate.

“This ‘back to the city’ movement of the creative class has a dark side,” Florida said. “Within those urban superstars, we also have a winner-take-all system. So, we have neighborhoods that are priced through the roof and other neighborhoods and other communities that are falling behind.”

The figures bear this out. In New York’s gentrifying areas (ones where rents have shot up, alongside a change in the socioeconomic make-up of residents), average rents went up 30.4% between 2000 and 2010-2014, compared to a 16.1% rise in non-gentrifying districts, a report by NYU’s Furman Center this year showed.

Florida says that battling inequality is essential for cities’ continued development. He quotes the great 20th century urbanist Jane Jacobs to warn, “when a place gets boring, even the rich people will leave.”

“That’s the core of the crisis of superstar cities. Will [they] become so boring and ‘blandified’ that the very diversity, the socioeconomic, the racial, the ethnic diversity, the class diversity that made cities so special–they’ll become essentially ‘gilded in’?” he asked.

“I look at New York City today–with warts and all, it does look more like a suburb,” he said. “If you look at what people are living in on the Upper East Side, in these new towers, [it’s] 3,500 square feet for a family of two, a parking spot in the garage or next to your unit … This morphing of what we used to think of as urban lifestyle and suburban lifestyle is really intriguing.”

But Florida, who calls himself an “urban optimist,” believes a tranche of forward-looking, progressive mayors (he cites New York’s Bill de Blasio, London’s Sadiq Khan and LA’s Eric Garcetti as examples) are actively tackling inequality and embracing a diversity that he thinks is crucial for any city to flourish.

“Can we solve this? I’m not sure. Are these tendencies, these market-based tendencies [which push up housing prices] strong? Yes they are. Are the same forces that power our growth dividing us? Of course,” Florida said. “But I’m at least hopeful that the fact that because cities are diverse, they’re going to force us [to act].”