In the long run, optical drives are going to disappear, but I would not hold my breath. CD sales may be declining, but they are still relevant, and while video rentals will inevitably become an online business, they are still mainly bound to DVDs.
While I would personally prefer to get my Macbook sans optical drives, I do not reflect the majority of buyers. The majority wants to watch DVDs during commutes, or in bed.
The future of the Air will not depend on strategic ideas, but mainly on commercial success. If Apple finds out that replacing broken hinges costs more than the hassle of putting the relatively few devices that are actually being sold on the shelves, they will scrap it. As they did with a lot of nice products in the past, such as the Newton, the Cube and the 12in Powerbook.
As it is, the MBA accounts for a small fraction of all Apple hardware sales. After serving as a testbed for new batteries and casings, updates have been conservative.
My personal bet: The main Macbook line will keep their spindles at least for most of 2010. The Macbooks will retain their cubic appearance for a while, too.