Maybe Mr Stark of White Harbour/ Barrowton will turn up in Stannis' army as Stannis' candidate for Lord of the North...
They have a candidate Stark for Stannis. Davos just has to go find him on Skagos. Then Robett Glover can lead the White Harbour levies for Stannis.
He was mentioned, I think. When people reference the rebellion, I think he was mentioned a few times.
There was a couple of other references in earlier books to Connington. Tyrion or Jaimie reminisce about his fate after the Battle of the Bells. So his name/ history was backdropped.