There have been rumors for a couple of years now that apps may go cross-platform, working on both macOS and iOS. This isn’t actually far-fetched at all, since developers already can use shared code to develop mobile and desktop versions of the same apps. However, a report from Bloomberg points to Apple releasing software development tools at WWDC to make this even easier.
Called project Marzipan, these tools will help developers, but typical users won’t see much difference. There would still be separate Mac and iOS apps, however those apps would share some of the same elements. It is probable that Apple has already used early versions of these tools to develop the News, Stocks, Voice Memos and Home apps, which are cross-platform.
This does tie into another rumor stream that predicts that Apple may one day ditch Intel’s processors for Macs and use powerful versions of the chips in iOS devices. If developers are developing universal apps by that time, it could make such a transition smoother.