What my dream is that the User Mode Linux is made into a cross-platform userspace binary that translates syscalls transparently between itself and the host. So

What my dream is that the User Mode Linux is made into a cross-platform userspace binary that translates syscalls transparently between itself and the host. So you might get "drivers" that talk to Windows, Linux, *BSDs, Darwin, it manages memory in an efficient (for the host) way, and enables you to run any kinds of wild experiments with, say, virtualized and passed-through serial devices, USB devices, networking, bind-mounting from the host and image mounts. And yes, containers. All of that without needing host root in most cases. Of course the drawback would be that the host would see just a fat Linux process and its child processes, much like you can see qemu, but it could be an interesting thing nonetheless, if even for shits and giggles of it.