Rumor has it they are adding a new quest for cores. You will pay 2 cores and then need to get 1000 head shots in competitive, do 500 zavala bounties, and tell Drifter you're sorry for snitching. In return you get a random item, which can be 1 core. Once you have done that quest 2000 times, you get the achievement "Ate paint chips" and a position at Bungie.