Builders and planning groups fear that lenders are drawing conclusions from the financial meltdown that will stunt the growth of high-rise housing, even after the economy recovers.

During an industry panel discussion on Wednesday, Michael Covarrubias, chief executive officer of San Francisco development firm TMG Partners, said that he doubted he would witness another residential skyscraper built in San Francisco.

"And you'll never see two towers again," he said, referring to projects that included twin high-rises, such as The Infinity and One Rincon Hill condominiums in the SoMa neighborhood. "It's the death knell for residential development."

If his prediction is true, it would undermine assumptions in long-range planning throughout the city. Notably, the Transbay project includes - and depends on land-sale revenue from - as many as seven new skyscrapers, filled with an undetermined mix of residential and office space.

Dean Macris, a senior adviser on the plan for Mayor Gavin Newsom's office, questioned Covarrubias' assessment.

"We're in a situation where we really can't predict, once we're out of this economic climate, what kind of building types will be finance-able," he said. "I don't see any reason for us to revise our thinking."

Covarrubias made his comments during a real estate discussion at the Yerba Buena Center for the Arts sponsored by the San Francisco Housing Action Coalition. In an interview, he explained that most of the residential towers erected in the city during the boom were financed by multimillion dollar loans in which banks took on 80 percent of the risk.

With those institutions foreclosing in rising numbers and swallowing steep losses, few will accept such lopsided ratios again, he said. That will boost the equity financing developers must raise from pension funds and endowments, money that comes at a higher cost.

"I don't think you'll make the numbers work again for a very long time," said Covarrubias, whose company co-developed the Soma Grand condo tower on Mission Street.

Michael Cohen, director of the mayor's office of economic development and another panelist, said he was skeptical that housing high-rises will come to a permanent halt, but acknowledged that such projects won't move ahead soon.

It's not just skyscrapers that are at risk, but mid-sized condominium projects as well, said Gabriel Metcalf, executive director of the San Francisco Planning and Urban Research Association. Once developers begin construction on condos, they and their financers are on the hook for the entire structure, he said. In contrast, builders can tilt up single-family homes one at a time, drawing down their loan in increments as the market dictates.

Those realities could repel and attract, respectively, lenders in a newly conservative mood, even though the latter development pattern has come under growing scrutiny. Suburban sprawl makes inefficient use of limited land and necessitates greater reliance on greenhouse gas-emitting automobiles, environmental and planning groups argue. In recent years, many builders and lenders have begun to embrace the urban infill alternative.

"My greatest fear is that the fallout from the financial collapse will be that sprawl development becomes even more attractive," Metcalf said.