In 15 years 50% of the USAir (East) seniority list will have retired. So a 10-15 year fence would protect career expectations on both sides.
Just my opinion though, I have no intention of accepting recall.
In 15 years most of the west (including me) will be retired.
As far as fairness, I was a few dozen numbers from upgrade back in 2005, on the arbitrators list (two years later) I'm even further from it so I'm NOT FEELING LIKE I GOT MUCH OF A WINDFALL!