There is no reason for a merger between a legacy and a regional since there is nothing to gain. The legacy already owns all of the flying. Mergers between legacies have worked by complimenting each other and expanding the network. Mergers between regionals can consolidate equipment and crews to better serve their contracts. A legacy only needs a regional to operate as long as it serves their needs. Being that legacies have zero problems filling classes, they don’t need all of the pilots either. They could pick and choose those that they wanted and never deal with the expense and hassles of a merger. The aircraft and flying could then be redistributed as they see fit.