First don't work for either carrier (DAL or NWA), but Cobra, you are absolutely right. Payrates/raises can come and go, but 'seniority' cannot be sold, unless You Give It Away.
And, seniority will be the most important thing going forward, for both sides. With oil at $120-140/bbl (or higher), and a looming recession, slowing of passenger travel, including Int'l travel (recent study showed First/Business class travel to Europe is down 4-5% in the first 4 mths of this year); with all of this taken into account, do you really think the New DAL (post merger) will operate a 750+ mainline a/c fleet???
Do you really think so??
New a/c deliveries can come, but merely replace older a/c that are retired, or worse yet, one new a/c and 2 older retired.
NEVER give ANY on Seniority!! A pay raise is nice, but seniority determines whether you have a job tomorrow, or next year.
For what its worth.