In May 2019 I published this:
Personally, I think this year is too early for ARM-based Mac. Why? Because, my thinking is that Apple wants iOS on these ARM-Based Macs, not Mac. And they want a lot of ready-to-use, yet well-known apps to be available. For this, they are working on Marzipan (which later became Catalyst) to entice developers to write more powerful apps for iOS, especially the iPad. These are the prime candidates to run on this future ARM-based Mac. We are four weeks away from knowing a bit more about Apple’s strategy. Source: Apple Is Done With Intel - Numeric Citizen Blog
The Apple Silicon was announced more than a year later.