Did Vikings drive out natives of the British isles?

Robert E. Howard's alternative version of history, one he sketched out in a letter to fans to describe the background for his fictional Hyborian age setting, read much like this. From The Glasgow (Scotland) Herald:

VIKING settlers may have "ethnically cleansed" Scotland's islands, waging a genocidal campaign against native Pictish tribes as they arrived, according to evidence uncovered by archaeologists. Excavations on Orkney could finally settle a centuries-old historical debate over whether the Norsemen integrated with indigenous locals or slaughtered them at the dawn of the last millennium. Work at Langskaill farm, in Westray, shows signs of a Pictish culture vanish abruptly with the arrival of the Scandinavians, underlining the theory that the Northern Isles were taken violently.