The potential cost of American Dream could still jump given Triple Five’s reliance on bonds at a time when interest rates in the bond market have been rising. Beyond that, the 2.9-million-square-foot project (bigger than the Empire State Building) is a daunting undertaking with other serious challenges, particularly in a state with no shortage of shopping malls and a county that prohibits retail sales on Sundays.

The $5 billion enterprise described by Mr. Ghermezian would require a daily gusher of customers to be financially viable, and he estimates that the complex will attract more than 40 million visitors a year, half of them tourists visiting New York City.

That sounds optimistic considering that only 12.4 million of the 56.4 million visitors to the city last year ventured to Lower Manhattan, according to groups that track such activity. Skeptics have asked why people would cross the Hudson River from the biggest theme park of them all, Manhattan.

Rosy forecasts for American Dream also fly in the face of predictions that, ultimately, Internet shopping will all but eliminate brick-and-mortar shopping.

“There are still a lot of questions marks,” said D.J. Busch, a senior mall analyst at Green Street Advisors, a real estate research firm. “The prospects are better with all the bells and whistles. But there is a lot of competition for wallet-share and time-share in the New York metropolitan area. If it was simply a mall, I would say the probability of success would be much lower.”

The project was originally conceived in 2003 when the state awarded the Mills Corporation the right to build Xanadu, a retail complex on the grounds of the state’s Meadowlands sports complex that was to feature a 286-foot-tall Ferris wheel, an indoor ski hill, a Legoland park, movie theaters, a concert hall and hundreds of stores.