Mignolet has not played for the Reds since January, while Karius has looked somewhat shaky in pre-season, his confidence seemingly impacted by his errors in the Champions League final.
Earlier this month, Liverpool parted with around £67m to make Alisson the most expensive goalkeeper in the world, and Klopp admits that he does not know what the future holds for his other custodians.
"We had the opportunity to bring in one of the best goalkeepers in the world," Klopp told Sky Sports News.
"Loris Karius and Simon Mignolet are both outstanding goalkeepers but we have outstanding midfielders and strikers and defenders but we still brought in [players in those positions] any way to help us make the next step. That is the world of football.
"Of course, can Loris be happy or Simon be 100% happy about the situation? I don't think so. How can people be happy like that? But it is part of life. I don't know [what their future holds]. We need to see that. We don't need 54 players and 20 goalkeepers. That's how it is."
Mignolet is believed to be on the target of Turkish giants Besiktas.