Overpopulation is not expected to be an ongoing issue in the upcoming century, but there is general consensus that hundreds of millions if not billions of people over that same time period are anticipated to enter current developed-world working- and middle-class living standards. And under our current understanding of household technology, that means a commensurate rise in consumption of white appliances. This new group of entrants into the white appliance markets are likely to have lower income profiles than their developed-world counterparts, due to the deflationary bias of ongoing globalization trends.
This confluence of factors could potentially open up an interesting and highly profitable business niche for a manufacturer that focuses on modular, repairable, maybe-hackable appliances.
Instead of promoting a consumption model where entire units are tossed out at the "end" of a "lifecycle", I can now concede a manufacturer could thrive on a far leaner capital profile than current industry participants where I wouldn't have thought it possible only 10 years ago, by focusing on the logistical tail of constantly repairing and improving "old" models, as opposed to concentrating on the new product manufacturing end.
This is also beneficial on the embedded energy cost and resource utilization efficiencies levels, which becomes extremely important as we scale up the population that participates in higher socioeconomic levels.
Human form factor-dependent design points can probably stay relatively static to benefit families in lower socioeconomic strata. For example, washing machines have not really changed their basic form factor in about a century. I'd rather sell a patching kit designed for my older tubs (a common failure mode) to those families today, enticing them to grab a used older model of mine than hope to capture them as customers ten years from now when they can maybe afford a new unit from me; it pulls in future sales without destabilizing debt schemes. Or if they can afford a little more, I can sell them a retrofit kit that supplies a newer future cleaning technology (like ultrasonic?) that fits older models. If they care about aesthetics, I sell them paint that exactly matches what they have on the old model.
All this while, I not only keep my units out of the landfill, but in the hands of more customers earlier than I normally could acquire them and out of the hands of my competitors in an inexpensive marketing/sales denial of service attack on that competition (and indeed, my customers are paying for that attack instead of me having to heavily spend on marketing to them). On top of this, my manufacturing costs shift increasingly out of the predations of the unpredictable turns and gyres of the commodities markets, and towards design (especially software) and small parts manufacturing. These can have higher margins than the whole units, and might be a lot cheaper than even JIT inventory to "stock" in the future, with local 3D-printing-style distribution centers for those parts that can be on-demand manufactured practically at point of sale. As the global population level stabilizes as currently expected, I'd already be positioned to sell into an economic environment where brand-new product purchases are made with increasingly razor-thin margins.
For those oldest models that fall below a logistical tail cutoff, I could release CAD/CAM and other design files to let hackers do what they will with those models, with the intent to temporarily boost those models popularity and continue to stymie competitors' entrance with customers of those models. When the cost of labor is low enough, making repairing and reconditioning possible can potentially be very remunerative for manufacturers who do not build around a business model of continuous, growing new unit sales (which in turn is predicated upon a continuous, growing population).