MAC air switch to ARM is a nice theory... But, more probably, the switch may be to INTC chips as by 2013, INTC will have more powerful and less power consuming 3D chips for the tablet market. Won't be surprised to see AAPL moving away from ARM totally and contract to INTC.
Disclosure - I hold AAPL, MSFT and INTC for the long term!
You missed it ! Ah! INTC moving to $35 which is the fair value given the current fundamentals, technology, cash holding, dividend and stock buyback! Can't think of a better shareholder friendly company!