Members of the city’s arts community have long dreamed that a performing arts center would one day rise in the Seaport District, a grand house for theater, dance, and music. As a version of that dream inches closer to reality, the new plan has triggered both excitement and many questions in the arts community, while drawing fire from some activists who say it would provide significantly less cultural space than an earlier City Hall-approved plan.

WS Development, which owns the 12.5-acre Seaport Square site, is trying to rally support for a proposed complex of theaters that includes a 500-seat house and two smaller venues to accommodate audiences of 100 and 100-to-150 people.

Principals at the firm say the proposed theaters — two of which would form the Seaport Performing Arts Center, or SeaPAC, with a third nearby — reflect the financial and physical realities of building in the Seaport while helping the city’s space-starved small and midsized performing arts groups.

The arts community has welcomed the prospect of three new theaters, saying they would go a long way toward addressing pressing needs.

Multiple arts leaders also expressed potential interest in operating the facilities, either as part of a consortium or as the sole operator.

But while WS has not specified the project’s square footage, it would probably deliver less cultural space than a 2010 city-approved plan calling for a 200,000-square-foot performing arts center or “equivalent civic space’’ within the L-shaped mixed-use development, which stretches between Northern Avenue and Summer Street and had a different owner at the time.

And although some arts leaders say Boston doesn’t need another large theater, the proposed complex only partially embraces suggestions made this year by the Boston Planning & Development Agency, which asked the developer to consider including an additional 800-seat theater, a flexible space for neighborhood artists, and an endowment to support their operations. WS has not committed to providing an endowment.

“I think you can expect to see some more evolution,’’ said Jonathan Greeley, director of development review for the development agency. “We’d like to talk to them about how you endow these places for success. We’d like to talk to them about: Are these the right number of theaters overall? Is this the right number of seats?’’

Yanni Tsipis, WS’s senior vice president, Seaport, said the firm’s revised proposal caters to many of the needs identified in the city’s recent facilities assessment survey, which found a dearth of affordable rehearsal and performance spaces for small and midsized companies.

“We took a great deal of guidance from the city’s performing arts facilities assessment study in determining the types and sizes of venues in the project,’’ Tsipis said. “The facilities assessment didn’t call for an 800-seat theater.’’

While reviewing the WS proposal, City Hall is listening to community feedback, said Joyce Linehan, the city’s chief of policy. “We are happy that WS takes seriously the commitment to cultural space the neighborhood requested in the original filing and that they are being guided by the cultural facilities assessment we commissioned,’’ said Linehan in a statement. “We will continue to work with them and we expect their proposal will evolve as they hear more from the arts community. Everyone’s goal should be for a successful and sustainable performing arts facility or series of facilities to result from this project.’’

For some neighborhood residents, however, the revised plan marks what they say is the latest in a series of Seaport developments in which civic and cultural space has taken a back seat to commercial interests.

“The history here is one of watered-down commitment,’’ said longtime Fort Point activist Steve Hollinger. “The 200,000-square-foot commitment could easily be smaller theaters and other cultural uses that add up to 200,000 square feet, but instead we’re not even talking about square footage.’’

Like Hollinger, green-space advocate Valerie Burns praised the city’s efforts to ensure a robust cultural component in the Seaport but said WS should do more. “The city has a full and vital vision of what should happen here,’’ she said. “I don’t think we’ve yet seen something from the developer that really approaches that fuller vision.’’

The arts community has been considerably more enthusiastic.

“People are still absorbing the news that there are going to be these theaters: That is historic for Boston,’’ said Maure Aronson, executive director of the arts presenter World Music/CRASHarts. “That is the most important and exciting news.’’

Still, big questions remain. Among them: Who will operate the theaters? Should they be endowed to offset staffing and maintenance costs? And once they’re built, who will pay for the lights, seats, stage, and sound systems?

WS’s Tsipis, who estimated the theaters wouldn’t be up and running for another three to four years, said it was too early to answer such questions.

“We are still in listening mode,’’ he said. “It would be premature to draw any conclusions about the best operating model for these venues until we hear all of the community feedback about the proposal.’’

There is broad consensus among nonprofit performing arts groups that the theaters — if they are to offer affordable rates for presenters — must have an endowment.

“If you’re not going to endow it, you’re going to need to charge market rates to offset the cost of the staffing,’’ said Julie Hennrikus, executive director of StageSource, an advocacy group. “And that means it’s subject to commercial forces, so the comedy show may win out over the small dance group.’’

Josiah Spaulding, chief executive of the Boch Center, agreed. “It would be my hope that the developer, besides kicking in the land, would also help to support that project financially,’’ he said.

Spaulding went further, suggesting that ownership of the new theaters might transfer to the city and be operated by a nonprofit.

“If it’s open to all, I think it becomes owned by the city,’’ he said. “The Boch Center would be interested in participating in that open public forum. We’d be interested in operating them for all, helping try to raise the money.’’

Another potential operator: the Boston Center for the Arts. Gregory Ruffer,chief executive of the BCA, said his organization wants “to be part of these conversations.’’

Meanwhile, a number of arts presenters imagined a consortium running the complex.

Gary Dunning, president of Celebrity Series of Boston, is considering the prospect but raised questions about groups teaming up: “That is a complicated negotiation: Who picks them, and what’s the condition of being part of the group — do you have to pay for part of the theater?’’

Aronson said that although he could imagine a matching endowment campaign between WS and the operator, outfitting the theaters is another matter. “The developer needs to do the build-out,’’ said Aronson. “The build-out is a lot of money.’’

Not everyone agreed an endowment was necessary.

Don Law, president of Live Nation New England and co-owner of the Boston Opera House, said demand for the 500-seat theater would be great enough that an endowment might not be needed.

“If they get a building built at a reasonable number, it should be sustainable,’’ said Law. “I think there’s enough strength in those organizations to make that real estate deal work without hemorrhaging money.’’

Esther Nelson, general and artistic director for Boston Lyric Opera, said SeaPAC would not address the needs of her company, which seeks a space with around 1,500-seats.

“The need for a larger facility dedicated to the larger not-for-profits continues to exist,’’ said Nelson. “If you want to call something a performing arts center in a city the size of Boston, it seems to me that it suggests something a little bit bigger.’’

Greeley said his agency wasn’t making a “purely square-footage-based calculation.’’

“We take very seriously the overall spirit of the obligation and the need for significant dynamic space,’’ he said. “We think that’s just as important as the square footage of the overall obligation, so we’re trying to find an appropriate balance.’’

Tsipis, who has been meeting with various performing arts groups, said the firm was keeping an open mind.

“It’s too early to close any doors,’’ he said. “We’re in the middle of a public process, so this is not a foregone conclusion that this is where we’re going to end up.’’

Malcolm Gay can be reached at malcolm.gay@globe.com. Follow him on Twitter @malcolmgay.