That extra 1.3” diagonal makes a huge amount of difference. The fact it will likely be a passively cooled machine means it won’t cannibalise the pro lineup in the same way the air started to with the 2014 and 2015 pros. They could adopt a similar pricing strategy as the 13” ntb MacBook Pro and start it equal to the 12” (cut to $999?) but with 128gb of storage rather than 256. Alternatively, they could go the +$100 for the larger model route like they did for the airs - pretty much equivalently specced the 13.3” was $100 more than the 11.6”.
This is a brilliant point, also it gives Apple the room to then remove the Air and the MacBook fits nicely in it’s place. Whether they will do this at an event later this year I don’t know, they could decide to announce them at the September event during a big keynote, similar to how they did the other year when the iPad Pro was first announced along with new iPhone’s and new Apple Watch.