I just picked a number out of the air, but a more rational number would be 100USD. that’s the max valuation at which it’s still possible to transact 0.01USD given the 0.0001 limitation. The billion coins won’t exist at the outset; according to the paper that number is projected 20 years after mining begins. At the end of year one the supply would be 25,750,000 * 100USD = 2,575,000,000. That’s still a lot, but what if it becomes a problem due to valuation? I wonder if it’s something that can be changed later?