a) Sure, Apple doesn't have a low end and as such higher overall margins, but: The Big Three all have a sizable mid-/highend/ultrabook/business range as well with just the same i5/i7/core m CPUs (only updated more often). Apple surely is a good customer, but I severely doubt that the overall margin difference for Intel between them and Apple is even in the remote vicinity of an order of magnitude. What is an o.o.m. higher though is the market share of those three (~60% vs ~6%).

b) I just don't see a bargaining chip. What's the "or else" from Apple's side? Full Ryzen? Would actually be cool, but Ryzen is still completely unproven in the mobile world, and this would be all the more reason for AMD not to enter the deal. ARM? Yeah...I wouldn't hold my breath.

You have to consider that this isn't a simple internal SKU customizing, but a significant and delicate licensing deal with THE direct competitor in x86 world. (The tech is actually the simpler part, seeing that it's not an integrated solution but a MCM.) Apple would have to have severe leverage that they would be the main driver for Intel for such a move. Or they are paying a real buttload for this tech - but then you can be sure they want exclusivity. And the statement really doesn't sound like it.