I expect Apple would not honor my AppleCare warranty if I brought my iMac 5K in with a large hole cut in the back for a high-end air or water cooler. And yet they still keep releasing new models, new form factors and new updates, even if not every six months like some desire/demand. And Mac revenues rose a record 9% last quarter because of it. Seriously, how many people would replace their Mac every six or twelve months just for a slightly better CPU or GPU? I did it once (5K iMacs) for the GPU (395 to 580) and even then, a year later I just bought an Alienware to play PC games and now wish I'd saved the money and kept my 2015 (and I received ~70% of my 2015's price back in re-sale). Even if Apple did update every six months and dump the old models to the Clearance Store like the PC vendors do, I don't expect Mac sales will suddenly quadruple and Apple will replace Dell and HP at the top of the charts. Dell and HP do it because the vast bulk of those extra PCs they sell are to companies and corporations to run Windows-based applications (their devs are likely on Macs or their PCs have Linux).