At the same time, the proposal still has a significant way to go. The plan – which needs to undergo the city’s uniform land use review procedure and an environmental analysis – can take between five or six years for all necessary and regulatory approvals.

Mitch Korbey, partner and head of Herrick, Feinstein LLP’s land use practice, tells GlobeSt.com that given the size of some of the buildings, demolition and rebuilding could difficult and may not be viable. “However, a number of these buildings were built in the 30s or 40s and in order to respond to the marketplace now and the marketplace in the future are going to be modernized and rehabilitated,” he says. “And given existing zoning which might constrain them in terms of their size, there’s not a lot of incentive to do that. What this rezoning does is give us a boost toward making these zones more economically viable and allowing them to increase in size. Therefore, it makes it more viable to improve the buildings and bring them to today’s marketplace in a way that makes them viable as class A office buildings.”

Korbey says there may be some instances where demolition becomes appropriate, especially with some of the mid-sized to smaller buildings. “With a zoning change allowing increased density, I think on a case-by-case basis, you’d have to look at it and figure out in light of newfound density, it does make sense to demolish and start over instead of making significant rehabilitation and additions to the building,” he says.

A big part of the proposal also depends on how hungry tenants are for new space, and how much if anything they’d be willing to pay as a premium on rents. According to mid-year data from Cushman & Wakefield, the overall vacancy rate in Midtown is 9.8%, the same as 2011, and asking rents have increased to $66.44 per square foot, a 4.9% jump. At the same time, renewal activity totaled 6.8 million square feet of activity, which is 1.3 million square feet less than all of the renewal activity recorded in 2011—a sign that tenants are more likely to stay put than move.

Tara Stacom, a vice chairman at Cushman & Wakefield who represents many of the city’s premier properties, including One World Trade Center, says the city is in need of “quality new construction” to keep the best tenants in Manhattan, and Midtown East is lacking it.

“At Grand Central, the city is starved for new construction,” Stacom says. “The tenants want it to attract and retain talent. They like open collaborative spaces, and these new buildings are much more efficient for tenants who are trying to cut costs everywhere. You can squeeze space standards much tighter because they are typically column-free. All of these benefits that a new building has is what is attracting tenants to the market today, and the more that these developers could be involved in new quality construction which the city is depleted on, they know that these buildings will absolutely rent.”

While there are costs involved to take a building down, re-tenant it and build a new one, Stacom says the value over time will be greater than pouring money into an older structure. “You really need to create new quality construction, which creates a much higher rent,” she says, which is prices around 30 to 40% higher than older stock.

However, legitimate questions about whether the infrastructure can handle the commutation pattern of the additional workforce into what we refer to as the Grand Central area is coming into play. According to statistics from the MTA, annual ridership on Metro-North Railroad, which passes through Grand Central, totals 82,037,786 riders, in addition to five subway lines in the area.

While the environmental impact statement and public hearings are yet to come, Korbey says the city should be poised to handle more density based on its existing infrastructure and capacity to handle a high volume of people. “We have to provide for the growth of Manhattan, the growth of the business district and overall the growth of the city. Although we are at our population peak right now, there are some areas of the city that aren’t,” he says, adding that: “You can’t use zoning just to react; zoning has to anticipate and plan for growth. And that’s a very important part of what the planning department is doing here.”

Howard Zipser, shareholder, Akerman Senterfitt, tells GlobeSt.com that the initial proposal has the potential to create a “significant opportunity for development,” but other outside factors – like market conditions – will determine if, and when, construction will happen.

“People think that zoning enables development, and that’s only partially true because what it does do is eliminate or streamline some of the process toward the approval of a proposed building, but it doesn’t relate to financing, interest rates, office demand and all of those factors have to coalesce with a zoning change or with a zone special permit which enables new development,” he says. “It is not simple, but it is certainly a first step. But just because the city fathers want to increase density, it doesn’t mean that development will automatically follow.”