Since SSD prices are still very high, and Apple is aware that pros want high storage capacity (500-750 GB), why not use a HDD/(blade) SSD combo, as they do in the iMac and Mac mini? Seems like the best of both worlds to me.
Unfortunately, it's sacrificing functionality for sleekness (which is not new to Apple, go back to the hockey puck arthritis mouse on the first iMac).
No optical drive (which I'm fine with) and no 2.5" hard drives...