Apple have recently released an article about the transition to 64-bit technology and how it will affect the future of 32-bit applications.
Apple began transitioning to 64-bit hardware and software technology for Mac over a decade ago, and all modern Macs now include powerful 64-bit processors that can run advanced 64-bit apps. These apps can access dramatically more memory, enable faster system performance, and take advantage of technologies that define today’s Mac experience, such as Metal graphics acceleration.
Apple has been working with developers to transition their apps, and in 2018 Apple informed them that macOS Mojave would be the last version of macOS to run 32-bit apps.
Read the full article on Apple’s website here