If we keep devices around longer then less e-waste in the landfill which is a good thing. Apple just needs to be able to offer more repair services such as component level repair for example and shouldn't charge you insale prices to repair their devices if they break.
Factory component level repair isn't going to happen. Even well before the iPhone, Apple (and a whole lot of others) manufacture final assemblies consisting almost entirely of modules. At the factory if a module is bad it gets a new module, they wouldn't do module repair. If a device later goes into their refurbishment process, bad modules are replaced with good modules.
Making component repair does not in itself mean longer lasting. Companies refine the mfg process to provide, they hope, a quality product as cheaply as possible and one that consumers will trust. This process (something Toyota was supreme at) is one of constant refinement. Modular has been a major plus to this process. Try to change that inorganically? The repercussions are an unknown.