The respectively bountiful supply in orbit could be, in theory, harvested at a sustainable rate. The harvested particles could be used for a variety of purposes.
Here's another post about the antimatter story, which I wrote about earlier today. A point I neglected to mention was that it isn't necessarily about mining antimatter. It seems somewhat akin to "farming" it. You see, it isn't making it, as in a particle accelerator. Rather, it is using cosmic rays to make them and then trap them before they can escape.