I'm pretty sure Apple has been developing and testing their own processors on macs, in parallel, internally for years. They did this prior to the Intel switch as well. Apple takes it's time and doesn't do something until they are sure. You may be right that they might miss or delay that target timeframe, for whatever reason. But they've been making their own processors, on macs. They will release them. It's just a matter of when. They will make the switch for the same reason they switched from PowerPC to Intel years ago because they are dependant on a supplier that isn't doing their part and they are being hurt by it. Or other reasons, like developing their own processors allows them to make things thinner or more power efficient or makes their development more efficient. or a number of collective reasons.