One thing is certain about tech gear: People are hanging onto their gadgets for longer periods of time. So I know a lot of people who are happily using Macs that are more than five years old. Indeed, just how much incentive is there to buy a new Mac anyway, assuming your existing machine is working correctly? Indeed, Apple helps the process along by supporting older Macs with the latest and greatest macOS.
So macOS Sierra will work on any Mac from 2010 or later, and a 2009 or later MacBook and iMac. This a pretty large range, even if it’s less than OS X El Capitan. It is true that older Macs will not support certain features, such as Metal graphics and HandOff, the ability to start a task on one Apple gadget and continue it in another. But for most of you, that missing feature won’t make much of a difference.
That doesn’t mean the experience is necessarily perfect otherwise. Users of older Macs very likely don’t have machines with SSDs, although they are available, even if you have to jump through a few irritating hoops to install them. So the presence of a traditional hard drive will make performance seem more and more sluggish. I can’t say if that phenomenon is the result of the higher resource needs, but it’s not at all unusual. In fact, it’s the main reason why I put an SSD in my 2010 17-inch MacBook Pro some time back. Waiting long minutes for startups and agonizing seconds to launch an app became just too much, and it only seemed to get worse year after year.