Also a satoshi cannot ever be worth U$ 1 because :
a) there isn't that much money in existence and;
b) Bitcoin transaction fees would be impossible to pay if the smallest unit of the cryptocurrency gains to much value. You can't break a 1 satoshi transaction down into microsatoshis. That would probably require changes to the core source code, perhaps adding 8 more zeroes.
Just FYI to correct this partial misunderstanding, the lightning network is already using sub-satoshi denominations. Second layer technology that lock-in bitcoin for other crypto-tokens, receipts, etc, like lightning and side-chains can program whatever smallest denomination they choose.