It's fully confirmed and everything. They even had interviews about it.
http://politiken.dk/kultur/article406641.ece
According to that article, they're coming back because they wanna have fun, even though they said many times they would never come back. But they just "felt like it".
They explained that they had gotten tired of each other and all they needed was a break. In the mean time, Lene and Søren got married and the group started to spend more and more time together - so it came natural.
The group says that they do not want to release a full third album, but maybe a greatest hits with new tracks. They feel like they want to focus on being a tour band and return to the stage.