Since Rybczynski wrote Home in 1986, there is, of course, no comment made in the book that can compare the concept of comfort today to the concept of comfort current in 1986. What you are being asked to do here, then, is to use your own inductive reasoning powers to make observations of present-day ideas of comfort then to make comparisons to what Rybczynski wrote about the concept of comfort in 1986. Then you'll make inferences about what you observe that will lead to explanations of how the concept of comfort is different today from what it was in 1986.
Briefly and by way of example, two areas where the concept of comfort is different today than it was in 1986 are in expansiveness of home and luxuries in personal living. Ironically, these two elements of comfort are contradictory and antithetical.
Expansiveness of Home: In 1986, spaciousness, great halls, and elegance of fittings for kitchen and bath were the trend. The bigger the home, the better. The more pronounced the elegance and features, e.g., built-in jacuzzis and built-in kitchen islands, the better. Presently, the movement in home comfort is toward compactness in which spaces serve dual or multiple functions. One of the most dramatic aspects of the compactness trend is the "Tiny Home/House," a bungalow home that can be portable and that makes use of lofts and dual-function spaces to create comfort from compactness. Another equally dramatic aspect is the "container house," homes made out of shipping containers. Interesting articles with pictures explaining this trend away from 1986 expansiveness toward contemporary compactness are "Tiny house offers different options for affordable housing" and "tiny houses" (more pictures).
Luxuries of Personal Living: Rybczynski's central metaphor for changing ideas of comfort is designer Ralph Lauren, who introduced mass produced designer label clothes, accessories and, later, home decor that was specialized by themes, like Mariner, Safari, and New England Farm. Because of Ralph Lauren's success and influence, designer goods migrated from the realm of the elite and wealthy to the domain of the working or career person and family. It began to be commonplace for adults to be judged by which designer linens they purchased (and the thread-count thereof) and for school children, in America, at least, to be judged by which designer and sports-person endorsed clothes and shoes were owned and worn. Comfort had ceased to be attainable in modest everyday items because comfort had escaped the every-day and lodged in elegant designer items.
Now, comfort necessitates suntan beds, professional manicures, and designer label work and career clothes. The complaint of the latest generations of young career professionals is that they will never have the nice things their parents have, which is true because comfort in the 2010s demands mobile phone packages, expensive grooming practices, designer clothes and shoes, and trendy new home furnishings. Their parents and their parents' parents made do with everyday comforts and saved money (not spent money) or worked hard for promotions until they could afford to do better and have bigger. Personal comfort today is found in spending while personal comfort in 1986 still (but not for long) was found in frugality.