The Ospreys star needs an operation to remedy a long-running shoulder problem which could rule him out for up to five months.
While the 2009 British & Irish Lion is still hoping to help his club win the Magners League title this season - they have made the Play-Offs - his season could come to an end after the Grand Final on 29 May.
A week later Wales are due to play the world champion Springboks at the Millennium Stadium on 5 June and a decision must be made whether or not to risk the utility back for that game and two Test tour to New Zealand soon after.
"James needs an operation and it just depends when. He could have the surgery after the domestic season with the Ospreys is completed or when he is back from the summer tour," said Wales coach Warren Gatland.
"But whenever he has it, he'll be out for anything between three and five months. I would have been happy for him to have had the operation before the Six Nations but the Ospreys wanted to manage him through the rest of the season."
Wales are already without Tom Shanklin, Mark Jones, Dafydd Jones and Gareth Cooper for the summer and Gatland might also be forced to leave behind three times Lions tourists Martyn Williams because of shoulder complications.