Downtown planners on Thursday rolled out a glitzy vision of Downtown Brooklyn as a 24/7 destination — and neighborhood — putting snazzy window dressing on a retrenchment of the original notion that the Flatbush Avenue corridor and surrounding streets would be a booming business district.

The Downtown Brooklyn Partnership, the quasi-governmental agency charged with creating the “new Downtown,” presented glitzy renderings (pictured) of what the area will supposedly look like in five years.

The slideshow, complete with a voiceover by stage legend Ian McKellan (Brooklyn Academy of Music’s own King Lear), forecasted that the area bounded by Tillary, Fulton and Jay Streets and Flatbush Avenue Extension, plus the blocks around BAM, would become “a true urban center.”

The Partnership predicted $9.5 billion in new private development that includes 14,301 residential units, 1,803 hotel rooms and 1.6 million square feet of new retail space. The animated renderings — plus the Partnership’s commitment to building a central park called “Willoughby Square” — will be used to help lure new investors to the area.

Absent from the Partnership’s presentation was mention of the city’s original plan for Downtown Brooklyn to become a booming business district. Where the Partnership once saw 4.5 million square feet of new office space, it now predicts 1.6 million.

“The 4.5 million square feet was the total capacity that could be created,” said Partnership President Joe Chan. “We don’t really see it as a failure. The growth of the commercial sector was one goal of the [2004] Downtown Brooklyn Plan. The other was the creation of a 24/7 community. Clearly, on the residential end, we’re doing better than we ever thought we would.”

Indeed, as Chan pointed out, three new residential skyscrapers have topped out in the past year: the Forte in Fort Greene, the Oro on Flatbush Avenue, and be@Schermerhorn. Several more have broken ground.

But the Partnership’s hope for a 24/7 residential community is facing the harsh reality of a sudden downturn in the real-estate market and on Wall Street — economic conditions that recently prompted Mayor Bloomberg to demand cutbacks from his commissioners.

The presentation was held on the 23rd floor of One Metrotech Center, an artifact of a previous Downtown Brooklyn redevelopment scheme, where Chan has his offices.

The Downtown czar offered these predictions:

• Within two weeks, a developer will be selected for a part of the BAM Cultural District, which includes the controversial new home for the Manhattan based Dancespace Project, an experimental group that is displacing a homegrown music venue called Amber Art and Music Space.

• Shortly thereafter, the city will select a developer for Willoughby Square, the 1.5-acre park and underground parking garage. The controversial project will require the city to condemn homes linked by historians to the Underground Railroad.

• By early spring, construction will begin on the Theater for a New Audience near BAM, and on the $15-million city-funded beautification of Flatbush Avenue, a gritty thoroughfare that Chan dubbed an “iconic boulevard.”