According to the seniority list ST put out this morning, the current average age of UPS line pilots is 52. Tthe 2016 seniority list plug will hit the historical junior CA seniority level (~65%) by the end of 2026 and hit 50% seniority in very early 2029, based ONLY on Age 65 mandatory retirements.
Early retirements, medical outs, and terminations will shorten that time...as will any growth to the pilot group beyond a nominal 2550ish size.
Yes, there are downside risks too...but hopefully past performance is not indicative of future results.