I don't have a guess at what Apple is actually going to do, but the Retina rollout is a plausible model. Even 5+ years after the first Retina product, it's stil

I don't have a guess at what Apple is actually going to do, but the Retina rollout is a plausible model. Even 5+ years after the first Retina product, it's still not available across the lineup. I don't think the switch would present a significant problem in marketing or for developers, so it would purely be a question of having the chips that fit the products. The Macbook, as you point out, is basically already there.