For starters, read the headlined article that observes that capabilities pre-date the UNIX model.
Even the "classic authorities" on this stuff, including Bach, Comer, Deitel, and Tanenbaum, pointed to many things that went beyond the UNIX model. And this was almost thirty years ago.
There is a wealth of experimentation and diversity that already exists and that has been done over the intervening many years. In addition to the operating systems already mentioned on this very page, there's Helios which was a capability-based system with a POSIX layer on top from the late 1980s/early 1990s. The BSD 4.4 Log-Structured Filesystem had global wear levelling in the filesystem in 1990. OS/2 1.0 went beyond terminal escape codes and multiple mouse protocols to a device-neutral video, keyboard, and mouse paradigm for TUI applications in 1987. People have done operating systems where everything really is a file, "object oriented" operating systems, network distributed operating systems, microkernel operating systems with multiple "personalities", ... all sorts.
For starters, read the headlined article that observes that capabilities pre-date the UNIX model.
Even the "classic authorities" on this stuff, including Bach, Comer, Deitel, and Tanenbaum, pointed to many things that went beyond the UNIX model. And this was almost thirty years ago.
There is a wealth of experimentation and diversity that already exists and that has been done over the intervening many years. In addition to the operating systems already mentioned on this very page, there's Helios which was a capability-based system with a POSIX layer on top from the late 1980s/early 1990s. The BSD 4.4 Log-Structured Filesystem had global wear levelling in the filesystem in 1990. OS/2 1.0 went beyond terminal escape codes and multiple mouse protocols to a device-neutral video, keyboard, and mouse paradigm for TUI applications in 1987. People have done operating systems where everything really is a file, "object oriented" operating systems, network distributed operating systems, microkernel operating systems with multiple "personalities", ... all sorts.