People often say that 'real' OSes are not architecture-specific. But how true is this really?
Clearly Linux is, but isn't that the exception?
The other Unixes appear to be mildly incompatable and architecture dependant.
Windows has only ever been available for x86.
Macs are migrating from PowerPC to x86; presumably they will at some point become exclusively the latter, perhaps with some legacy emulation for old apps.
In contrast, mobile phone development is apparently a nightmare of different hardware specs, making each machine a different platform in practice, even though the OS might be the same. And this is holding things back.
Obviously, software manufacturers like to distribute binaries rather than sources, and as few as possible of those.
It seems to me that in some sense commercial operating systems become single-architecture due to this normalising force. Macs are not becoming multi-architecture, but transitioning from one to the another.
Linux gets away with this by distributing sources and having sysops as users, who know how to type 'make'.
Even if ROS were open-sourced, this wouldn't happen for commercial apps.
So. Sure the hard-coded ARM nature of RISC OS means that it isn't easy to transition to another chip architecture. But the processing-power dominance of x86 is likely to be transitory. It would make more sense to try to migrate to multi-core ARMs than non-ARMs. By hudge or by kudge, providing that it can be made elegant in later revisions.