It has been confirmed that the upcoming World of WarCraft Expansion, Wrath of the Lich King will be releasing only on DVD, this includes both the standard and Collector's Edition. This shouldn't be an issue as the majority of computers ship with a DVD drive and the face that DVD drives are fairly cheap now. The alternative for people without a DVD drive is to wait for the digital download to appear, which unfortunetly did not appear for Burning Crusade until two weeks after the retail launch. Best of luck to all who are without a DVD drive right now, you should be able to pickup a new drive before then, or have a friend who has an external.
Source: World of WarCraft Europe Forums
More...
Source: World of WarCraft Europe Forums
More...