Hardware is upgrade-able on laptops. At least, all the laptops I've dealt with. Now, it's not AS upgrade-able as a desktop, but you can get higher capacity RAM chips, bigger harddrives, etc.
See, I know that, but I also think that you could sacrifice some slimness/compactness for up-gradable components and there would be a good amount of market for that if the OS was good and the feature was marketed right. (I mean, commercials almost write themselves - show person frustrated by their phone being outdated 6 months after they get it - BAM - show happy customer with upgrade-able phone.)
To be clear, my contemplation about this had it starting as providing either replacement motherboards or replacement SoCs and flash storage (if the storage is separate from the motherboard/SoC respectively, the OS could be made to check the storage for a backup image of the SoC's storage when booting on a blank SoC, and the SoC could theoretically be used to store at least basic settings and the like when you swap the storage, though you'd have to use other storage for the rest of the data). You wouldn't be replacing RAM/CPU by itself, because that WOULD cost a shitload in R&D to develop right without it being huge, and you'd need to make your own hardware at that point, but I think replaceable motherboards/storage/antennas (upgrade from penta-band to whatever if you need more, upgrade to a 4G or 5G antenna when your carrier rolls that **** out, etc), that would be a start. I think it's genuinely doable, even for a start-up, if you manage to get just a handful of skilled embedded device hardware engineers, some good marketing, and a ****-ton of money for the hardware contacts with various factories.