Apple is a much bigger platform than RISC OS and can no doubt fund the move(not that it would be their first change of architecture) to Intel x86 chips. Here on RISC OS, we have trouble shifting to newer ARM chips, letalone a completely different platform. IMO RISC OS platform today has neither the funds or the resources to do such a move. Besides, we have the Iyonix, the forthcoming A9 and already a two forked OS - Do we really need another fork that will be completely incompatible with the other two? As newer and quicker ARM chips are produced, no doubt we'll get quicker RO machines, should there be sufficent market demand.
I believe the RISC OS platform has navigated very treacherous and murkery waters these last few years, and whilst the seas have calmed somewhat there is still a long journey ahead of use before we see the beautiful green land that we once knew.