It is a well-known fact that AmigaOS is a single address space, totally unprotected memory operating system. The original implementation ran on a Motorola 68000, that did not support virtual memory if not by external hacks, and later models and OS version did not support it either due to retrocompatibility issues.
On the other hand, Exec's memory allocation routines accept a (no-op) MEMF_PUBLIC flag that the last official AmigaOS 3.1 Developer's Kit defines as:
MEMF_PUBLIC This indicates that the memory should be accessible to other tasks. Although this flag doesn't do anything right now, using this flag will help ensure compatibility with possible future features of the OS (like virtual memory and memory protection).
So I'm prone to think that there was at least some research internally to retrofit some memory protection/paging/swapping capability in the OS.
I also remember rumors in 1990/1 of an implementation that should have been integrated in a version of the OS past-2.04/V37.
Was this ever real? Did developers receive beta versions of the implementation?
ADDITION: I'll add that I'm not really interested in later solutions of the post-Commodore era (such as AmigaOS 4.0), and that I'm aware of what is written on AmigaOS 4.0 documentation page Obsolete Exec Memory Allocation but I don't really agree with most of what is written there.