Thanks guys for your answers , but I still have an other question to ask : according to what you said , bitcoin is going to be rare , right? So its price will be more valuable , won't it?
Bitcoin itself will become "rare" in the future, but the technology around it won't.
The question is going to be if something that is technological way superior to bitcoin, would be able to effectively replace bitcoin. See ethereum for example.
But then again, some people don't hold bitcoin for the technological aspect, but more because of their ideological views.