If I read that correctly, I don't know where you're extrapolating that Apple is making this move to replace macOS with iOS / a walled-garden where nobody can create apps for Mac except by selling them through the App Store. If Apple wanted to do that, they would just sell iPads and stop selling MacBooks.

As for 2), I think that's a nice convenience - if you're a developer you wouldn't have to to worry about emulation.

> does anybody have faith that Apple is going to be able to navigate a rewrite of macOS on this scale

Is it really that crazy they would rewrite parts of their OS to target a new architecture? A large undertaking sure, but not that ridiculous... This is Apple, not some random startup lol.