Super,
You won't lose any numbers or relative seniority unless of course your expectation is to staple. Although a merger could add 1,500 pilots to the seniority list a merger will also include 100+ airplanes, block hours and new routes. In other words, staff neutral. Your opportunity with Delta, in the end, will remain the same.
Consolidation is a different issue. Nobody wins if that happens.
BTW, it might come as a surprise to learn that most if not all at Alaska are happy flying the equipment and domestic routes they do. WB and long-haul international would be of no interest. As a result, Life-long fences would be expected...and fair.