For those who are wondering if whether or not they will be needing to make an upgrade, one of Apple’s slides during WWDC revealed which Macs will be compatible, and the good news is that it looks like support will go back at least 7 years. For those who own the 2009 or later iMac or MacBook (when it was still made of plastic), you guys are safe.
As for other Macs, as long as your MacBook Air, MacBook Pro, Mac mini, or Mac Pro was bought in 2010 or later, you will good to go as well. This covers a fair number of Mac computers, so if you were worried that you’d need a new Mac for the rebranded macOS, chances are unless your Mac is still one of those candy-colored computers, you’ll be fine.
Note that there are many older Macs that were compatible with OS X El Capitan that have not made the list. macOS Sierra has been set for a release later this year, but developers who are part of the preview program can look forward to a beta next month.