I guess that an Intel x86 based RISC OS is not really to be expected. Just think of the work RISCOS Ltd claims to be necessary to make Select run on a 32 bit ARM processor (that is the XScale) and not just on older 26 bit ARM processors (that is StrongARM and the like). And I didn't get Select for my A5000 either despite RISCOS Ltd stating that they want to make Select available to all RISC OS systems
So I do have the impression that it would be too much work to make RISC OS run natively on an Intel Pentium or so. RISC OS 5 does run on an Intel processor though
But a VirtualRPC (or VirtualIYONIX) not needing Windows but sitting on top of some Unix type system like Linux or MacOS X would be an intersting one...