The launch of a [new] desktop Mac without an optical drive...put me in mind of the launch of the original iMac in the late 1990s and the paradigm shift in computing which that machine signaled. Back then, Apple were the first to identify that the floppy disk was obsolete; slow, unreliable and lacking the capacity needed for contemporary computing. The iMac was designed from the outset for networked environments and the internet. The rhetorical question Apple asked was 'why would you need a floppy drive if you have email?'.
[Now] in 2011 [we have] the strongest signal to date that optical media is becoming (in computing terms at least) moribund...Software and data are distributed via networks or the cloud and on those increasingly rare occasions where you have no network connection, portable flash storage is cheap and ubiquitous.
[The move away from optical media seems to mark a notable change in the storage and transfer of digital information and will have real implications for recordkeepers]. It's not that long ago that high-quality optical media was being recommended as a good 'vault' for digital information...Similarly, [we are] approaching a situation where we have to keep an optical drive around which can be plugged into a more modern machine to resurrect the only known copy of some important file, in the same way as we've had to keep floppy drives around for some years now...[Does] Apple's decision to ship a desktop computer without an optical drive point to impending obsolescence in the same way that the iMac's lack of a floppy drive did 13 years ago?
Chris Foresman, writing for Ars Technica, has answered that question, at least as far as Apple is concerned:
Apple has drawn the line in the sand: optical discs are out, and digital distribution is the future...
It is important to remember that Apple is only one company and lots of other manufacturers will continue to include optical drives with their PCs. However, Apple has in the past offered a strong indication of the direction of travel in technology and that is why their decision to move away from optical media is so interesting.