In April, 2021, Apple Computer launched its mid-year products refresh. Apart from a finder beacon and the oh-so-exciting "the color purple", prominently featured was the new Imac. Its primary selling points are that it has the new Apple M1 CPU, and that it’s "impossibly thin."
When designing for sustainability, there are a number of considerations, including longevity, repairability, and modularity. Longevity refers to how long the unit will operate normally in its default configuration. In general, the smaller the box you put something electronic into, the more heat will build up. And more heat means shorter life. Now I assume Apple has taken this into account and installed a decent air flow system. Repairability includes the ability to access internal parts as they fail. Apple has often scored quite low on repairability (as rated on sites like iFixIt.com). Certainly this unit will be all-but-impossible for third party technicians to repair, not only due to the compact packaging but because of Apple’s traditional refusal to release documentation or replacement parts. And on the issue of modularity, you can probably just forget it.
Two counter-examples that come to mind are the Teracube 2e phone and the Framework laptop. The Teracube is about twice as thick as the average iPhone or Google Pixel phone, but it is highly modular. The Framework is remarkably thin for a laptop, but their web site talks about the issues around heat, and how they designed special cooling systems to deal with that. And their machine is certainly modular.
I think it’s safe to say that the 2021 iMac’s 'Impossibly Thin' will mean it is all but 'Impossible to repair' for everyone other than Apple. That’s like if you couldn’t take your Chevy or Toyota to anyone but a Chevy or Toyota dealer to get the oil changed. The technical term for this is "vendor lock-in". As in, you are locked in to one vendor for all future service. Maybe Apple customers are OK with that. I’m not.
(Update: Forbes agrees with me).