LaGuardia Airport is a symbol of all that’s wrong with the region’s aging, decrepit infrastructure. It’s dark, dingy and crowded. Flights are perpetually delayed and routes are cramped — you can’t fly much farther than Chicago, with a few exceptions.

Now imagine what could be.

Think of packing a suitcase for a non-stop flight to Los Angeles, and starting your journey with a subway ride to Willets Point in Flushing. A walk across the platform puts you on an AirTrain that whizzes over Grand Central Parkway traffic. You arrive at a gleaming LaGuardia Airport. The concourse is spacious and bright, with shops and restaurants. You glide through well-designed check-in and security areas, to a gate with seating, amenities and Wi-Fi.

It’s not just a dream. It is a likely picture of the future. And it may happen sooner than you think, mostly because Gov. Andrew M. Cuomo has encouraged the Port Authority of New York and New Jersey to get out of its own way.

On Tuesday, Cuomo and Vice President Joe Biden announced that ground was being broken on the $4 billion makeover of LaGuardia. It’s the start of a lengthy process — but its success is dependent on the public-private partnership the Port Authority has created. The authority is not a builder, and has correctly recognized its limitations. When it has tried, too often it has failed, or come in over budget and very late.

This time, the Port Authority is working with LaGuardia Gateway Partners, a group that includes Skanska USA, a construction firm; Meridiam, a fund manager; and Vantage Airport Group, an airport operator. The consortium is putting in $200 million of private equity and $2.4 billion in bond financing it closed this month. The group will be responsible for cost overruns and delays. Terminal B is scheduled to be done by 2021. We’re told to expect it to be on time and on budget, and we do.

The approach, we hope, will separate LaGuardia from the Port Authority’s past troubles, like the $4 billion Oculus subway station at the new World Trade Center. But even as shovels have dug into the ground, there’s still much to do.

*The key to LaGuardia’s transformation is to replace a patchwork set of terminals with a unified, connected airport. Delta Air Lines, state officials say, will redevelop terminals C and D. Placing terminals closer to the Grand Central Parkway can improve how planes taxi to the gates and ease long runway waits. But the plans must be finalized. State officials hope Delta’s updates will be completed simultaneously with Terminal B. That’ll require coordination.

*The plan for an AirTrain from Willets Point is far less certain. It will require a joint effort between the Port Authority and the Metropolitan Transportation Authority, and that isn’t simple. The MTA has issued $7.5 million in contracts for early engineering work on the Long Island Rail Road and No. 7 train stations at Willets. That could pave the way for a potential AirTrain stop, but there’s still much to do. Officials also hope to add a ferry stop near the Marine Air Terminal. That’s a smart use of the water at LaGuardia’s edge.

*To truly remake LaGuardia, the Port Authority should consider allowing longer flights. That would require a change to the “perimeter rule.” The rule, which dates to 1984, prohibits most flights beyond 1,500 miles (with the particular exception of Denver). Longer, larger flights can bring more passengers, fees, profits and revenue. But there are consequences, including the possibility that shorter flights to locations across New York and nearby states will be pushed out. Explore ways to keep those flights, but let the market work, and don’t discount the potential of opening LaGuardia to transcontinental flights.

*Revenue is key. City, state and federal officials should consider new ways to fund airport infrastructure and upkeep. There have been calls, for instance, to increase the federal passenger facility charge, a $4.50 per-ticket fee that hasn’t changed since 2000. It’s unlikely to happen, but the Federal Aviation Administration has proposed allowing the fee to be used for on-site rail. That’s a good idea. Then there’s a proposal from city Comptroller Scott Stringer, who suggests ending NYC’s sales tax exemption on jet fuel. That could bring in $100 million to $200 million a year, dedicated to the airports, officials said. It could help to fund the publicly paid portion of the renovations, the AirTrain, and other infrastructure. It would require state legislation, but it’s worth serious consideration.

*Even if everything falls into place, getting there may be painful, with disruptions and headaches for passengers. The Port Authority says it will have a third-party inspector general oversee construction, and will make significant efforts to communicate with New Yorkers. That’s important.

This will be a big challenge. One official compared it with performing open-heart surgery on a runner during a marathon. But a winning finish will fulfill a lot of flights of fancy about a far better airport.