Apple will never ever take macOS and change its UI to be optimized for touch. Or at least if they do, it’s time to sell the stock. They already have a touch UI, and it’s called iOS. They’re converging the two operating systems by making the underlying frameworks the same… the UI is literally the only thing they shouldn’t converge.
I like the fact that a number of iPad and iPhone apps now run on macOS without a simulator or any ceremony. While they are touch-optimized, they're easy enough to use with a pointing device. The gotcha to such mythical OS convergence is the inverse is untrue since a desktop UI is unusable 1:1 on a tablet with the coarser granularity of tapping and less keyboard access.
Perhaps OS-level AI in the future will be able to automatically follow design guidelines and UX rules and generate a usable UI (Storyboards or such View parts) on any platform given a description of data, its importance, and a description of what it should try to look like.
Even if a macOS VM had only a CLI terminal and a few core apps made by Apple, using a Swift UI framework that was compatible with a touch interface, it would be a huge step forward for iPad owners who are currently limited to slow and power-expensive emulation (iSH, ashell). Apple could create a new app store or paid upgrade license entitlement for iOS-compatible macOS apps, so that users can pay ISVs for an app version with iOS touch input.