Affordability is one of housing's more freighted notions.

For people or households with no- or low-income, affordability typically means subsidized, public-private partnership housing that may mean the difference between a bare-essentials abode and the a sidewalk grate or homeless shelter for the individual or household.

For the mass of others of relatively modest means, the term affordable mostly corresponds to a plus or minus gap between median incomes and media prices to either rent or own a place to live. National Association of Home Builders economist Rose Quint updates the latest available data in the NAHB/Wells Fargo Housing Opportunity Index (HOI) here.

Will take-home pay for such-and-such a household, either a single earner or more than one, be enough to pay monthly costs related to rent or principle, interest, taxes, insurance, energy, and transportation ... plus the rest of what it takes to live the relatively high quality of life we've come to expect here?

Quint notes that a titch less than 3 out of 5 homes sold in the fourth quarter of 2016 clocked in at sales prices that households earning a median income of $67,700 could afford. Quint's analysis provides no subjective commentary. Still, can you spot the "red flag" in her statement below?

The national median home price increased from $247,000 in the third quarter to $250,000 in the fourth quarter. Meanwhile, average mortgage rates edged higher from 3.76 percent to 3.84 percent in the same period.

For those whose businesses focus on the for-sale, single-family home building and development sector of housing--the one that has an outsized positive impact on the broader economy--affordability measures, on a market by market basis, the percentage of homes sold in that market that people with the market's median income can buy.

Mention the word affordability in a room full of home builders and developers, and many of them immediately conjure the image of a young adult household, struggling with early-career income uncertainty, student debt issues, a mismatch between good jobs and attainably priced housing, etc.

This is understandable. True and necessary balance in the for-sale ecosystem requires healthy demand, supply, and absorption of entry-level homes by households on track toward realizing the American Dream.

Still, this year, in 2017, it's a mistake to conflate for-sale housing affordability challenges into a Millennials-only issue.

Activating the next-generation 55+ market, which is the entry-level market for Baby Boom generation households in or on the verge of their next adventure in living, is equally critically important in the near-term for housing's slow-as-molasses recovery to stay on the rails.

Here, from Wall Street Journal staffer Timothy W. Martin, is a piece that might serve as a wake-up call for those who believe that affordability is only a young-adult challenge. Martin writes:

People in the U.S. ages 65 to 74 hold more than five times the borrowing obligations Americans their age held two decades ago, according to an analysis of federal data by the Employee Benefit Research Institute, a nonpartisan, nonprofit policy researcher.

Paying it off won’t be easy. Median savings for U.S. households nearest retirement age has dropped 32% in the past decade to $14,500, according to an analysis of federal data by the Economic Policy Institute, a left-leaning think tank.

People laugh when you [or I, actually] suggest that "flyover" country may hold promise for smart developers and builders in the next 10 to 30 years.

The issue is this. When interest rates do start seriously climbing--in relative terms--those monthly payments start to mean more and more, whether it's for a young adult whose income is low and heading up, or an older adult who's at the tail end of the wages timeline and heading into fixed income.

In 2017, affordability is going to matter not just for young adults but for older ones too, and it's going to impact land strategy, product development, and profitability for years to come. This is why it's critical to understand more and more precisely where your home products and communities match to a specific universe of qualified, predisposed, and potentially satisfied buyers. This is what our friends and sibling company associates at Metrostudy eat, sleep, and breathe.