This is stolen from my post in another thread but I thougth it had relevence here.
I think Apple's laptop lineup should be as follows: 11" and 13" MacBook Airs with the current form factor (or perhaps a slimmer bezel), boosted specs and retina displays! (what I'm waiting for, cash in hand!) 13" MacBook with an optical drive and SD display, which I believe we've seen the specs of already. The drive is necessary for this model because the market for this, the cheapest of Apple's portables is by and large those that don't want the expense of an external drive and may not even have home wireless (mums and grandparents) or who find the concept of a wireless optical drive intimidating and confusing. 15" and 17" MacBook Pros sans optical drive but with powerful discreet graphics, retina displays, SSDs only, all the fastest connectivity and quad-core processors. In other words, the ultimate portable performer in a slim and much lighter form factor and without the much-derided glass screens. They could have new strong and light glossy and matte screen options with ultra-thin aluminium bezels around the screen. This is Apple's ideal portable lineup because it's slim, has all the bases covered and none of the models are competing with or overlapping each other's niche. I really can't see the point of having a 13" MacBook Air, MacBook AND MacBook Pro! Yes Apple, you can give me a highly payed executive position! :P
Just like when Apple introduced the unibody design, the 17" will probably make its appearance later.