Finally some Mac News!! I hope they will bring Retina to the entire lineup. Also, I am very curious what Apple does with the MacBook Air. The MacBook is thinner and lighter than the MacBook Air, and I know a lot of people who are confused about this. So something needs to change there.
My guess would be an iPad Pro running iOS when used as an iPad and when attaching a Keyboard it will switch to OS X. That would make a lot of sense to all this Continuity features.