The other eight will come in 2014
Microsoft announced at this year's E3 that Xbox One would launch simultaneously in 21 markets around the world. Today, it's backing off from that promise by quite a bit. Instead of the scheduled 21 countries, it will initially release in 13 countries.
The markets that are getting the short-end of the stick are Belgium, Denmark, Finland, Netherlands, Norway, Russia, Sweden, and Switzerland. Microsoft has cited localization issues such as language and voice support, and partnerships as the reason for the delay. These countries are now scheduled to receive Xbox One "as soon as possible" in 2014.
For everyone that pre-ordered Xbox One in the countries affected by this news, Microsoft is throwing in a pack-in game with the console. Microsoft still intends to launch Xbox One in November 2013 in Australia, Austria, Brazil, Canada, France, Germany, Ireland, Italy, Mexico, New Zealand, United Kingdom, and United States.
Xbox One Launch Markets Confirmed [Xbox Wire]