When Delta re-upped its co-brand card agreement it set a bar that other airlines have tried to chase with their own bank issuer arrangements. American Express was willing to back the truck up to Virginia Avenue since it was set to lose its Costco cobrand and desperately needed to lock in its next-largest co-brand deal. (Shortly thereafter they re-upped their next largest, Starwood, as well.)
Revenue from American Express has continued to grow as spend on their products has grown. As Delta shared this week at is Investor Day 2017 revenue from American Express will total $3 billion. And they’re projecting out continued straight-line growth.