This would definitely make us re-think the ancientness of European matrilines if true. Although we're still far less clear on which mtDNA haplogroups came to Europe when than we are with Y-DNA, I know some researchers are leaning towards certain subclades of U5 and maybe U4 as being the principle paleolithic-origin European mtDNA haplogroups. If that's the case, then there is little discrepancy between the ancientness of patrilines and matrilines in Europe, as U4+U5 have comparable distributions in Europe as Y-DNA haplogroup I. It would also give evidence to the "recent arrival," or "fellow-traveler-with-PIE" theory of Basque origins. So, there's a lot of interpretation that hangs on this... hopefully some smart people can sort it out.