Something to keep in mind regarding the 12" MacBook: In 2012 Intel was telling partners that 10nm would be ready by 2015. In 2014 they pushed this back to 2016. It took until mid-2016 for Intel to admit that it wouldn't be ready by the end of the year. Ice Lake wouldn't end up shipping until late 2019.

It's crazy to think about, Intel 10nm was supposed to be available for the entire butterfly/touchbar era.