The delivery of the de Blasio administration's housing plan comes against a backdrop of alarming statistics and high expectations. Given the enormity of the goal the mayor set during the campaign—to build or preserve nearly 200,000 units of housing—and the centrality of housing costs to the dynamics of inequality in the city, the talk will be a defining moment for his mayoralty.

People probably have been worried about housing in New York since Wall Street was the city's northern border. It was certainly a concern even early in the Bloomberg years when the former expanded his affordable housing plan not once but twice. But lately there have been signs that the crisis is more severe than previously thought.

Last week, Comptroller Scott Stringer released a report that detailed the scope of the problem the city is facing—one of decreased affordability all along the income ladder and sharply rising rent burdens among lower-income New Yorkers that the private market is simply incapable of relieving. The Furman Center last week reported that nearly 600,000 New Yorkers paid more than half their income in rent and the Times this morning had an in-depth piece on the housing woes of the city's seniors.

De Blasio has received no shortage of ideas on how to address the crisis. The Real Affordability for All Coalition has proposed a detailed plan whose centerpiece is a move from an 80-20 model (in which 20 percent of the units in new buildings are affordable) to a 50-50 model, in which—depending on the neighborhood—half the units are market-rate and half are affordable, or half the units are targeted toward moderate-income people and half to lower-income families. According to the Observer, a sizable number of City Council members have endorsed that plan. Others have also weighed in. The New York League of Conservation Voters circulated a petition demanding the mayor's housing plan emphasize sustainability provisions. Manhattan's borough president called for more creative use of vacant land. The Association of Neighborhood Housing Developers blogged its suggestions.

Housing is central to the problems of inequality and displacement—or fear thereof—that drove so many New Yorkers to seek a change of direction in last year's election. Housing is the biggest expenditure of almost all households, and housing costs have been well outpacing income growth in the city. The inability to afford rent in neighborhoods that are suddenly popular among the more affluent is what makes gentrification scary. So housing policy is integral to de Blasio delivering on his promise to do something to make New York more fair and secure for people of moderate or little means. It's also integral to the fortunes of the real-estate industry, with which de Blasio has always gotten along. It will be interesting to see how the plan treats developers and owners.

Here are the other things we'll be watching for:

Preservation vs. new construction: Creating affordable housing can mean building new units or taking steps to keep units affordable through physical rehabilitation, purchasing, providing financing and the like. New construction is appealing because it actually adds to the housing stock, but it's very expensive. Cost concerns drove the Bloomberg administration to de-emphasize new stuff and increase the focus on preservation in its housing plan. How will de Blasio divvy his promised units up?

Permanence: One of the ways the Bloomberg team met its preservation targets was by coming up with creative ways to keep Mitchell-Lama developments and others from going market-rate after the lapse of the 30-year periods mandated by their subsidy contracts. It'd be nice if the de Blasio plan didn't set up a future mayor for such a crisis. But permanence usually costs money.

Income groups: Affordable for whom? This became a mantra in the latter part of the Bloomberg administration, which subsidized housing for families making well beyond $100,000 a year. De Blasio said in his 100 days speech: "We believe in affordable housing that reaches through the whole income spectrum. Folks who make the least, up through folks we would consider working class, and middle class." The argument for that approach is that the city needs a diverse economy and that many households who aren't poor face a real housing crunch. The argument against it is the city shouldn't be spending scare resources on people who could survive in the private market. We'll see how detailed de Blasio is on this point.

Homeownership: Homeownership was a small part of the Bloomberg plan but over the past three decades it's been an important way to build families' assets and stabilize neighborhoods. The foreclosure crisis, which is still playing out for many homeowners, obviously derailed those benefits for too many New Yorkers. What role, if any, will ownership play in de Blasio's plan?
Supportive housing and seniors

Development: A key part of de Blasio's campaign platform on housing was mandatory inclusive zoning, in which developers enjoying density increases are forced to provide affordable housing. But for inclusionary zoning to generate significant units, a huge number of market-rate housing units must also be built. Given all the concerns about density and displacement after the Bloomberg-era building boom, is there a plan for where to put all this new housing?

The money: In his campaign de Blasio suggested tapping into the city's massive public employee retirement funds for money to support affordable housing. But it's unclear how feasible that would be and any funds secured that way would be limited. The city can borrow money to building housing but New York's debt is already considerable. Real Affordability for All has called for mechanisms like a "flip tax" to generate dollars for low-income housing. Will de Blasio embrace any of these?

Political reality: Its common for New York politicians—including de Blasio—to talk very optimistically about the prospects for getting helpful money or policy changes out of Albany or Washington. Repeal of the state's Urstadt Law, which concentrates power over rent stabilization in the state's hands, is one popular rallying cry. After the mixed bag de Blasio received from Albany in the state budget, one will have to ask how realistic any City Hall wish-list is.

Stabilization: Much of the city's existing stock of affordable housing is considered as such because it is rent stabilized. But as rents rise more units get removed from the stabilization rolls as their monthly charge crosses a state-imposed threshold. Some have called for a freeze on stabilized rents, an idea the landlord lobby, understandably, hates.

Code enforcement: If housing isn't liveable, it doesn't matter how cheap it is. The Bloomberg administration implemented several new initiatives to improve housing code compliance, and de Blasio himself highlighted the issue in his Worst Landlords lists. A code crackdown could be part of a comprehensive housing plan.

Public housing: NYCHA is often treated as a separate subject from privately-owned affordable housing but the 180,000 apartments the authority manages are a key part of the affordable housing picture. And the land at some NYCHA developments has figured into past development schemes. Will de Blasio offer a version of the Bloomberg land-lease plan that offers more low-cost units?

Homelessness: Again, this is often treated like a separate issue, but most of the 52,800 people who were in city shelters on Monday night are human examples of what un-affordable housing does. Advocates for the homeless want to see more affordable housing units set aside for people leaving shelters. And de Blasio's team is working on a subsidy program to replace the failed Advantage scheme. Will details be delivered?

Housing court: The courts are a mechanism to protect New Yorkers from eviction and unsafe housing conditions. But they're widely seen as unfair and ineffective, in large part because most tenants go to housing court without any legal counsel. Will de Blasio suggest a way to shore up this bulwark of affordability?