I posted one of the articles linked in this article a while back (without much discussion). The author did stop by and post a link to this article, which talks a little more about the consequences:

http://phenomena.nationalgeographic.com/2013/05/07/charlemag...

and this paper, which uses DNA analysis to look at ancestry in Europe:

http://www.plosbiology.org/article/info:doi/10.1371/journal....