The fixed supply is the unique quality of Bitcoin which should tell anyone that having a share of the 21 million coins is a rare privilege that should be properly used because with such fixed supply and ever growing population of humans and awareness of Bitcoin, it is just normal to know that the demand will for the scarce Bitcoin will be highly valuable. 

I don't think there will even be more Bitcoin apart from the 21 million that were initially created most of which have already been minned.