There’s a new timetable for Apple’s Marzipan initiative to merge iOS and macOS applications, Bloomberg reports today, with this year’s Worldwide Developers Conference (WWDC) kicking off the effort for third-party developers and 2021 concluding the effort with universal apps. The new timetable expands upon a December 2017 report that Apple was preparing to bring apps originally developed for mobile iOS devices to Mac laptop and desktop computers.

According to Bloomberg, Apple will release a new software development kit this year to enable third-party developers to port iPad apps to macOS. The release is expected at the 2019 WWDC, which will reportedly take place from June 3 to June 7 in San Jose, California.

This step was expected after last year’s WWDC, when Apple confirmed that it had internally ported several Mac apps originally developed for the iPad, including Home, News, Stocks, and Voice Memos. The finished apps were released with macOS Mojave last fall.

In 2020, Apple will reportedly enable third-party iPhone apps to run on the Mac — a challenge, given their smaller, taller interfaces — while 2021 is the target deadline for a “single binary,” one app that can run on the iPhone, iPad, and Mac without needing to be submitted to separate App Stores.

As previously explained, this effort will ease the development process for third-party app makers while providing the Mac with a dramatically larger flow of compatible applications, following years of more vigorous mobile app creation and iteration. Universal apps could mean more revenue from developers, a single subscription that works across multiple devices, and code that could more easily run on next-generation Mac processors developed by Apple rather than Intel.

Apart from the new software development kit, Apple is expected to follow its traditional macOS and iOS release cadence at this year’s WWDC, with the first macOS 10.15 and iOS 13 beta releases as the stars of the show. Today’s report also indicates that the long-awaited modular redesign of Apple’s premium Mac Pro desktop machine could be previewed at the June event.