While every other consumer electronic device seems to shrink more every day, portable CD players have remained more or less the same size for years. Obviously, this is mainly due to the fact that the player must be large enough to accomodate a CD (120 mm, if I recall correctly.) Mini-CDs (80mm) aren’t a viable alternative as they can only contain about 20 minutes of music, about a quarter of the capacity of standard CDs.
A standard-sized DVD, on the other hand, has a capacity of about 4.7 Gigabytes. If the proportion of 120mm to 80mm disc capacity is similar to that for CDs, then a mini-DVD should in fact hold a good bit more data than a full-sized CD does. This would allow for the creation of much smaller portable players that still have the ability to play full-length albums. The only problem I can see is the inability to play (or fit, for that matter) current 120mm discs. In time, though, that problem would diminish as mini-discs become the standard.
So, at long last, the question: Is there any reason that this won’t or shouldn’t happen?