But Miami Art Museum leaders say they’re worried about what the downsized city park will look like, and whether it will be ready in time for their grand opening, scheduled to coincide with the arrival of the international art hordes for the Art Basel/Miami Beach fair in early December 2013. They’re especially concerned about the critical promenade, without which they say the museum could not open.

Their worst fear: Having an unfinished mud pit at their doorstep just when they have the attention of the international art world. Almost as bad, they say, would be a bare-bones park that detracts from the impact of their lavish new building, designed by the Swiss architecture firm Herzog & deMeuron.

“We remain very concerned about the quality of the overall scheme,’’ said MAM director Thom Collins. “Think about it. The park could be such an incredible amenity. This is the last parcel in that crown of downtown waterfront. It should be a real jewel. Our building is going to be beautiful. The plaza will be incredible. Our immediate landscaping will be beautiful. But what will happen south of there is in question.’’

Aside from plans for the simplified baywalk and promenade, the city has released no plans or renderings of the scaled-down green space, nor issued any descriptions of its scope. No work is apparent at the park.

Fiscal reality

Several mature trees, uprooted from the site of the Brickell CitiCentre project, were recently moved to the park by the developer, Swire Properties, and clumps of Bicentennial Park trees survive. But the center of the park space — used for special events like the Cirque du Soleil tent — remains a bare, treeless desert.

Sarnoff said the scaling down answers the city’s fiscal reality.

The Omni CRA special taxing district, which was to finance the full-fledged Cooper Robertson park, saw revenues drop significantly during the economic crash and has yet to fully recover, he said. The agency is also now on the hook to repay a $45 million loan the city took out to cover its share of the under-construction PortMiami tunnel, leaving relatively little cash for the park, he said.

The bulk of the baywalk is being financed by the Florida Inland Navigation Board, a special taxing district that pays for improvements along the state’s coastlines and financed reconstruction of the site’s seawall. The Omni CRA, meanwhile, is contributing about $5 million toward the park.

The Museum Park plan, including the new homes for the art museum and the science museum, was a cornerstone of former Mayor Manny Diaz’s efforts to revitalize downtown Miami. The museum buildings are being funded through a combination of Miami-Dade County bonds and private donations.

The park portion was included separately in the so-called mega-plan that Diaz negotiated with Miami-Dade County to simultaneously finance the PortMiami tunnel, the new Miami Marlins stadium and affordable housing in Overtown, using in part revenue generated by the Omni and Overtown CRAs. The tunnel is halfway done, the stadium is open, and the Overtown CRA is set to consider a plan to issue $50 million in bonds to subsidize several new housing developments in the historic but impoverished black neighborhood.

Some wonder if the promised park will ever materialize.

“It’s a shame, really,’’ said Science Museum director Gillian Thomas, whose building is scheduled for completion a year after the art museum is done.