Apple encourages the switch to 64-bit with 'not optimized for Mac' message
Today Apple started its push of 64-bit apps. The company's desire to banish 32-bit software and move everyone to modern, 64-bit versions is no secret and now it is starting the process of encouraging people to make the switch.
With macOS High Sierra 10.13.4, messages will start to appear when 32-bit apps are run. They say "[app name] is not optimized for Mac" and they only appear once so as not to be a pest, but it's a gentle nudge for users and developers alike that the future for Apple is very much going to be based on 64-bits.
Apple has not said exactly when it will stop supporting 32-bit apps, and it's likely to still be some way off in the future -- but that day is still drawing closer. To help explain what is going on, the message features a Learn More button. When a user clicks this, they are taken to a help page which explains:
To ensure that the apps you purchase are as advanced as the Mac you run them on, all future Mac software will eventually be required to be 64-bit.
The page also says:
Apple began the transition to 64-bit hardware and software technology for Mac over a decade ago and is working with developers to transition their apps to 64-bit. At our Worldwide Developers Conference in 2017, Apple informed developers that macOS High Sierra would be the last version of macOS to run 32-bit apps without compromise.
The 32- to 64-bit switch is something that's already happened with iOS, and macOS users can hardly say there has been no warning. Still, when the big day finally rolls around, there will almost certainly be complaints nonetheless.