Alaska Airlines is losing its partnership with Delta. In my view that was a better deal for Delta customers — who could earn more valuable miles crediting to Alaska Airlines Mileage Plan when flying on Delta, which worked out well especially for discounted domestic first class — than it was for Alaska Airlines customers who couldn’t even book Delta award seats at half the miles for a one way award.
Nonetheless, Alaska is going to great lengths to make sure its customers come out ahead with their acquisition of Virgin America (so a bigger route network on which to earn and burn) and by reducing the cost of domestic economy short haul awards and increasing mileage-earning on partner premium cabin tickets.