If there is enough adoption 21 million coins is not enough to go around. ... If 21 million people were interested in bitcoin the price would easily head north of 4 figures.
I strongly disagree, for this simple fact: one satoshi carries exactly the same transactional capability and benefit to consumers/merchants as does one full Bitcoin.
People need to get over the mindset of $1/
BTC1, i.e., value being assigned in integer increments.
The current Bitcoin protocol provides for a maximum of 21M BTC x 100M sat = 2.1 QUADRILLION units of fungible supply.
Ben