I see only downside, in terms of seniority, for the Delta pilots in a merger with AK. I am sure there would be short term fences for the widebodies. Many Delta pilots will have AK pilots slotted in senior to them. Those AK pilots currently have no rights or ability to fly a widebody. The only way to protect the career progression of the Delta pilots would be career long fences, and I really don't see that happening.