What eventually happened to the viking in Ireland?

Answer 1

First answer:

they settled, intermarried and became an integral part of Irish society

Second answer:

That's the standard answer but Y-DNA studies have indicated otherwise. A Study by McEvoy et al stated "The Vikings (or Norse) played a prominent role in Irish history but, despite this, their genetic legacy in Ireland, which may provide insights into the nature and scale of their immigration, is largely unexplored."

..."The findings are consistent with a relatively small number of Norse settlers (and descendants) migrating to Ireland during the Viking period (ca. AD 800-1200) suggesting the that Norse colonial settlements might have been largely composed of indigenous Irish."