Not sure if you are aware of this, but Bungie has already been paid. They created a product for Activision to sell, and Activision paid them for it. Any additional money made on DLC, microtransactions or whatever else they sell may earn Bungie a small royalty, but most of it goes to Activision. Bungie is not the type of business that has to sell something every day, every week, or every month in order to stay afloat. Whether or not Destiny continues to be playable is up to Activision.