At WWDC Monday, Apple announced that this year’s macOS High Sierra will be the last macOS release to support 32-bit apps “without compromises.”
Starting in January 2018, all new apps submitted to the Mac App Store must be 64-bit capable and, as of June 2018, both new apps and app updates must be 64-bit capable. Submissions not matching these requirements will be rejected as a matter of course.
@ScottB: This has been the case with iOS for quite some time now. No new submissions or updates can happen unless the app is built to 64-bit.
What about 64-bit apps for iOS?