Gotham Gazette has an excellent look at the effects of "a housing bust" by Queens College demographer Andrew Beveridge. This map shows how much income goes towards mortgages; Beveridge notes:

The median income of those paying less than 30 percent of their income on housing is $120,900. For those paying between 30 and 50 percent of their income, though, the median is $74,390, and for those paying over 50 percent the median income is $39,900.

Not surprisingly, the areas with the highest proportion of income going for home ownership costs are in Queens (especially Jackson Heights, East Elmhurst and Corona), Brooklyn (notably Borough Park, Greenpoint/Williamsburg, Bushwick, East New York, Ridgewood, Cypress Hill, Highland Park and New Lots) or the Bronx (in particular Morris Heights, University Heights and Fordham.) Manhattan homeowners do not appear to be spending more than they can afford to anywhere the extent of those in the other boroughs.

Related: Home sales across the country keep going down.