I'm assuming you meant 8 core about the top end BTO? If so, that makes a lot of sense... If Apple were able to get that extra 400 MHz out of the top end i7, that solves the problem. I'm not at all sure the 15" Pro will be a spec bump. Apple's been unusually forthcoming about the keyboard for something they aren't planning to fix soon, and there's the rumor about a 16-16.5" machine.
Two thoughts about the 15" Air. One is that some substantial number of (unspecified, but low power) Sunny Cove chips are supposed to be shipping in summer/fall (but how many times have we heard that story)? They may or may not be the right chips, even if they do ship...
The second is that the chips from the 13" Pro would serve - even though they're technically 8th Generation.
Two thoughts about the 15" Air. One is that some substantial number of (unspecified, but low power) Sunny Cove chips are supposed to be shipping in summer/fall (but how many times have we heard that story)? They may or may not be the right chips, even if they do ship...
The second is that the chips from the 13" Pro would serve - even though they're technically 8th Generation.