By saying this might be the last home that someone purchases, there is nothing implied that it needs to be or has to be. The premise is that by carefully considering what someone's needs are in terms of space, layout, features, the potential for addition or expansion, the quality of construction, technology present, and sustainable elements included, a person can be very diligent about acquiring a home for themselves - new construction or existing - that possibly can serve their needs long-term and potentially as long as they need a place to live.
Some people make impulse decisions and buy a home like they do a car or piece of sporting equipment - they liked it, it fit a need, and it was priced right for what they were looking for - so they bought it quickly without giving it that much additional thought. Besides, if they decided that they had chosen badly, they would put it back on the market and find something else better suited for them.
As aging-in-place professionals, we can help people choose wisely if they desire a new home. Real estate salespeople can do the same. Unfortunately, people often chose a home for themselves for the location, the appreciation potential, the monthly payments, the school district, and other factors that will not stand the test of time.
If we were to tell people that withing the next few years, they had to research and decide upon a car that they had to keep for the rest of their lives, imagine how much time and energy they would put into this project. We need to help people apply this same strategy to the selection of their next home - beginning at a younger age than we might normally think would be the case.
What is so terrible about helping someone in their twenties or thirties pick a home that is comfortable, safe, accessible, and appears to be able to meet their needs as they project them out in time and consider how they might want to use that home?
Of course, people who already have a home that they like or that works reasonably well for them - even if they didn't pick it out that way and just kind off "lucked out" - we have a huge responsibility to engage them to make sure that their homes continue to age well with and for them. If they don't need to get another home because their current one is right for them or can easily (and perhaps inexpensively) be made to do so, that's what we should encourage.
Buying a long-term home as the next one, or turning the existing home that people have into that forever home, makes sense on many different levels. That captures the spirit of aging-in-place.