Right now, the old Suffolk Downs race track exudes that particular type of melancholy that’s unique to places that are about to disappear.

Regulars still place simulcast bets inside the clubhouse, leaving a smattering of cars in the parking lot. But the huge grandstand sits empty, and the track itself is idle. The knowledge that Seabiscuit raced here in 1935, and the Beatles played to 24,000 screaming fans in 1966, only reinforces the feeling of faded grandeur.

Spend a few minutes talking with developer Thomas O’Brien of the HYM Investment Group about his vision for the property, though, and your spirits are likely to lift.

“As you can see, this is a big site,” O’Brien said recently, standing on the unused track’s edge. “It’s 161 acres, so it’s by far one of the biggest sites that can be redeveloped in the greater Boston area.”

And when that redevelopment is complete, O’Brien says — in 15 or 20 years, if everything goes as planned — the new neighborhood that will sit on this spot will be a gem.

“Great restaurants where people can enjoy a nice meal,” O’Brien said. “Great parks where people can be outside and stroll and walk and exercise ... 25 percent of all the area will be dedicated to open space.”

And, O’Brien adds, Suffolk Downs 2.0 will provide a major boost to the Boston area’s legendarily constrained housing stock, with 10,000 new units straddling East Boston and Revere.

“I’ve been doing this work for 25 years, and I have to tell you, there were decades here in Boston where we didn’t build any housing at all,” O’Brien said. “We really feel like this site can be part of the solution to the crisis.”

Which is exactly what Boston City Councilor Lydia Edwards wants to happen. But unlike O’Brien, she’s not convinced the new Suffolk Downs will be part of the solution just yet.

“If done right, it could be one of the greatest things that happened to our community,” Edwards said. But, she added: “Done wrong, you end up with the Seaport.”

The Seaport, of course, is the neighborhood that sprang up, seemingly overnight, on the South Boston waterfront, boasting plenty of high-end housing and retail but notably lacking in diversity, public space, and overall character.

“It doesn’t really seem like a neighborhood at all,” Edwards said.

To prevent a similar outcome at Suffolk Downs, Edwards has a very specific request. In Boston, developers have to make 13 percent of the new housing they build “affordable”— meaning, for example, that a family making 70 percent of the Boston area’s median income, or about $75,000, could rent an apartment for about $1,800.

For this neighborhood-to-be, though, Edwards has another number in mind.

“Twenty percent affordable housing is something I’d like to see the developer get to us,” Edwards said. “I just don’t think 13 percent is enough to house the folks who are being displaced in Boston, and also ensure we have a growing middle class, and have a neighborhood that involves working people.”

That’s a particular concern right now in East Boston, where new developments reminiscent of the Seaport are springing up near gritty older homes that cost a lot more than they used to.

“If you look at any building where they have affordable units, for 40 units, they might have 6-7,000 applicants,” Edwards said. “We do not have enough affordable units.”

According to O’Brien, however, Edwards’ 20-percent-affordable ask is a nonstarter.

“The cost of building these units is very expensive, and it's very hard to add new costs to that,” O’Brien said, putting the cost per unit at roughly $500,000. “And so we really we just can't see a way that we can make that math work.”

That said, O’Brien agrees with Edwards that the Seaport is a cautionary tale of sorts — in part, he says, because multiple developers were involved. He vows that the new Suffolk Downs will be both much greener and far more welcoming.

“You can see … there are fences at either end of this site,” O’Brien said. “And so while people have maybe been able to look at this infield, nobody's been able to walk across it for 80 years.

“Once we take those fences down, once we start building the open space, then we can bring people in.”

Still, as the project works its way through Boston’s planning process, that disagreement over affordability could become an impasse. Because while O’Brien says 20 percent affordable housing isn't possible, Edwards says it’s a must.

“Technically,” she said, referring to the city of Boston, “we still have the final say.”