It's already too late, the UX already adjusts on touch as we witnessed in the demo. I don't think we'll be going back once people get used to it.
All the apps will likely have to be compatible with both modes as well moving forward.
My kids have touch-screen Windows laptops.
I absolutely hate the experience. It adds so little over a good trackpad.
And now Apple may force UI components to be big enough for touch control….