Almost a decade ago, the State Legislature signed the Hudson River Park Act, a bill that set out to transform Manhattan’s moribund, formerly industrial western edge into a vibrant riverfront parkland; it would not only promote health and boost land values, but would pay for its own upkeep with rents from three isolated, on-site development nodes at Pier 40, Pier 57, and Chelsea Piers.

While the miles of bike paths and green space have filled in just fine, the other half of the bargain has not come so simply, as community resistance to large-scale development has clashed with easy, if obtrusive, solutions. Despite years of searching and numerous companies willing to build, the park lacks a developer for both Pier 40 and Pier 57, an inaction that, if continued, could threaten the self-sustainability model.

The Hudson River Park Trust board, controlled by the governor, mayor and Manhattan borough president, last week opted to neither select nor reject the Related Companies’ bid to put a massive $625 million entertainment complex on Pier 40, further thrusting the pier’s future into limbo. The move came a week after a multimillion-dollar bid to create an Italian-themed marketplace on Pier 57 collapsed after almost three years, leaving the Chelsea Piers sports and entertainment complex, 13 years after its creation, as the one and only selected developer on the three sites.

Issues on the piers tend to drag on. The trust first received development proposals for Pier 40 more than a year ago, and in 2002, the trust first tried to find a developer for the pier, ultimately turning down feasible plans disliked by the community in order to “wait for a more favorable economic climate.”

At best, the inaction suggests growing pains for the self-sustainability concept, where kinks in the public-private model are gradually worked out. At worst, the imbroglio is a sign of worse times to come, where the trust could be forced to either invite a development reviled by the community or substantially cut back on park services.

City and state officials say the latter scenario is unlikely, though they concede that a fair bit of give will likely be needed on the part of local residents, whatever the end result.

“The community has to understand that without this being a successful operation that will draw down a great deal of income for the park as a whole, the community will suffer because there won’t be adequate money to put into the park,” said Adrian Benepe, commissioner of the city’s Department of Parks and Recreation and a trust board member.

The status quo is also not an option: Pier 40 generates more than $5 million annually in parking revenues in its current state, though the clock is ticking on its continued ability to do so. Chunks of the decaying cement roof have already rained down on parked cars, and officials say that areas of the pier could be closed off to parking due to the dire conditions. Tens of millions of dollars in upgrades are needed structurally as well as cosmetically—an infrastructure investment that is expected to come from whatever entity eventually takes the helm at the pier.

FOR NOW, THE precise paths of movement on both Pier 40 and Pier 57 are not clear. The trust intends to issue another request for proposals for Pier 57, according to Diana Taylor, chairwoman of the trust board; perhaps Chelsea Piers will bid to expand its operations there, as it did three years ago before ultimately losing out to the Witkoff Group. Community Board 4, where Pier 57 is located, tends to be more forgiving of large-scale development than are residents of the West Village, but it is unclear what proposals will come along, and there was some community resistance to Chelsea Piers’ bid.

As for Pier 40, elected officials and many in the community had high hopes for a proposal by a neighborhood resident group, called the Pier 40 Partnership, which would bring in a nonprofit owner and mildly alter current uses of the pier. At the trust board meeting last week, Ms. Taylor, the chairwoman, opted to defer on any decision on the Related plan, which formally responded to a request for proposals, instead indicating that the trust would like to see some mixing and matching.

“We cannot quash the RFP right now, because if we do that, we would have to issue another one and nobody would respond,” Ms. Taylor told The Observer. “We have these two responses to the RFP and the Pier 40 Partnership proposal—none of them work financially, so we need to compromise somewhere in order to make something work.”

The murky directive to try to cooperate seems to have left Related and the Pier 40 Partnership unclear on how to proceed. Partnership member Rich Caccappolo said the group’s previous attempts to devise a plan with Related met little progress, with the vision of a nonprofit aimed at infrastructure improvements and minimal traffic clashing with that of a private developer that needs to see a financial return in order to be at the table.

“We’re glad to take part, we’re glad to try to make that happen, but we have met with the Related guys many times,” Mr. Caccappolo said. “It’s really a hard equation to solve, and most people who would look at it would be back into this scenario of ‘I need to put high-impact uses to replace the costs there.’”

So with no clear path almost six years after the trust first began seeking a developer for Pier 40, and Pier 57 starting with a clean slate almost three years after Witkoff was designated the developer, are there other options?

Some in the community have suggested the city and state chip in maintenance or more money toward infrastructure at the park, lessening the need for major private development. Assemblywoman Deborah Glick, who has been outspoken in opposition to the Related proposal, suggested self-sustainability was not a be-all, end-all in the original Hudson River Park Act.

“I think people have to go back and reread the legislation,” Ms. Glick said. “The legislation never said that every last penny to keep the park going has to be generated within the park.”

(The official wording in the act is that operations should be paid for by the commercial uses “to the extent practicable.”)

Though, with the city and the state facing multibillion-dollar budget gaps, trust board members hardly seem interested in dipping into government coffers any more than already necessary.

“The park isn’t finished yet, and there’s no knight waiting to ride to the rescue here,” said Mr. Benepe, the city parks commissioner. “Given the economic realities, the city and the state have already made a significant investment in this park.”