Ripple could never dethrone bitcoin. Price wise, by just comparing their total supply, it could never exceed bitcoin's achievement. And with the community bitcoin is having, bitcoin will continue its reign over other cryptocurrencies.
I think you have a point there but it is not all about the total supply of a coin but usage and importance. Bitcoin is blockchain and decentralized, thus, orders can not be manipulated so to speak.
Also, in terms of maximum supply, I think in terms of bitcoin, it is there to be monitored as to the genuity of the totality otherwise I know of certain coin that has just 7million maximum supply but it price is just $0.0243