What happens when we don't need to exchange BTC for another currency anymore? Or will BTC be forever inherently dependant on the existence of a government contr

What happens when we don't need to exchange BTC for another currency anymore? Or will BTC be forever inherently dependant on the existence of a government controlled currency? How would we price things in BTC like groceries or salaries? Would that be always changing because the value of BTC would be forever going up? I'm probably talking beyond our lifetime here..