Here's what I'd like to see: a fresh desktop OS that actually innovates in the space. Desktop UX innovation has slowed drastically in the smartphone age, and for Apple it's come to a screeching halt (Windows - dare I say - is now the leader in desktop innovation). The fact that OSX is the only modern desktop OS that doesn't have window snapping out of the box is simply shameful. Even Ubuntu has it now, without any Gnome extensions.
Despite all this, OSX still has a huge foothold as the developer platform of choice - especially for web - because of its combination of quality hardware, Unix-ness, and relative stability (though all of those are becoming harder and harder points to defend). Apple should take advantage of this and throw power users a bone. We've been waiting for years on end. Stop working on useless things like the Touch Bar and start rethinking what a desktop operating system can be in 2018.
Unfortunately, what would probably happen if they built a new desktop OS is iOS with mouse and keyboard support, and developers would leave in droves.