I would honestly love to see a ground-up rebuild, but not the kind that would probably happen. OSX is getting creaky; it seems like it's had an increasing number of integral bugs lately, and the "redesign" that came with Yosemite felt more like a rushed coat of paint than a substantial rethink of the UX. Here's what I'd like to see: a fresh desktop OS that actually innovates in the space. Desktop UX innovation has sl…
Meanwhile, user-controllable per-process (or per-app) sandboxing would provide tangible benefit to all of us. This means, easy controls for accessing filesystem, network, cpu, gpu, memory, peripherals, and other processes.
Most of these controls exist, but in ways that don't map well to the desktop environment. How do I see what that adobe agent is doing? Sure, I can buy Little Snitch, but this should really be built into the OS. Too much of the UNIX model is designed to secure a user's information from other users, which simply isn't a massive concern these days when we often have dedicated workstations and have issues trusting the processes we run as our own user. What if I suspect my TODO list has a built-in bitcoin miner? I should be able to limit its use of the CPU and GPU.
Meanwhile, my editor still needs to read the configs of all my sandboxed apps, and whatever else I want it to access. This isn't necessarily an easy problem, but it's one I have confidence Apple could tackle, especially with mobile paving the way already.
All this time, docker has been innovating on the sandboxing, with mostly positive results. Android, I believe, runs each process as its own user, leveraging the existing UNIX controls better. I'm not sure what precisely iOS does, but it's locked down well enough to cause me immense frustration building stuff for my phone--not exactly what I'd like to see on the desktop, but they clearly have the ability to provide many of the controls I am looking for on the desktop.
I'm sure this would result in an improved UX as a result, TBH.
If not, Google is coming down the road with Fuschia.