Hashi is mainly for 3v3s, and he does not get replaced by kage barrier ninjas. The whole purpose of hashi is to manually override barriers should you lose initiative, or if your opponent refreshed their barrier with snake. For things like group instance, auto barriers are really bad since the AI will override yours between waves.

Minato is a collector's ninja, purely for fun. Creative ways to stomp much weaker players is fun and all but... he is pretty useless in a serious fight between similar powered players.

I don't have much to say about hiruzen, as I do not have experience with him.