It may have been... but not now.
That's why I think there's those new rumors about Apple making a new 'cheap' Macbook Air are true. It's something of a temporary replacement for the Macbook. Maybe it'll come with the Kaby Lake 8130U which has already been announced and looks like the Cannonlake U replacement.
Personally I wouldn't be surprised to that "cheap" MacBook Air just being the same Broadwell machine with a $100 price cut... and then they discontinue it in 2019.
Apple has been strategically letting the MacBook Air stagnate since 2015, so that in 2017 it actually benched slower than the Y series chips in the 12" MacBook. I'm not sure I see Apple suddenly giving it a much faster CPU, given that it's a legacy product now that's likely soon to see the chopping block.
As for Cannon Lake getting delayed yet again, it wouldn't be so bad if it's just a few months. And compared to Kaby Lake Y which on paper came out Q3 2016, Cannon Lake Y coming out in Q3 2018 isn't really that bad, considering the initial Kaby Lake Y was kind of a half-assed launch IMO. The mature stepping of the Kaby Lake Y line (which included a key multimedia upgrade across the line, as well as a vastly faster Core m3) didn't come out until Q2 2017.
Judging by what everyone here is saying now, it is looking like:
2018 spring: Coffee Lake U quad-core with GT3e and I'm thinking the i7 will be at least 1.7 GHz.
Speed boost over previous generation may be around 30-35%.
2018 spring: Coffee Lake H hex-core with GT2.
Speed boost over previous generation may be around 30-35%.
2018 summer: Cannon Lake Y dual-core.
Speed boost over previous generation ???.
2019 spring: Ice Lake Y quad-core (although IntelUser2000 has cast some doubt about Thunderbolt 3).
Speed boost over previous generation ???.