if Salah follows him to leave can Liverpool replace the duo with other players? I think it's really difficult to do as much as Liverpool can keep one of them, because Liverpool really rose because of the cohesiveness of their striker to become the best in the EPL.
It's hard to imagine if Salah and Mane left.
Letting Mane and Salah leaves is a loss for Liverpool, their lifespan is not too old. They are still capable of playing for a long time. If they want a raise the salary is natural. They have played well and have contributed to the achievements of the club. If they leave Klop will certainly have a hard time finding a replacement. Right now they are in ideal team conditions they only need to correct a few mistakes in the season. Maybe buying a few players will add to them getting stronger.
If both Mane and Salah leave Liverpool next season, Liverpool will face a lot of problems. The Liverpool team is stable and strong. But their performance is largely dependent on the performance of Salah and Mane. So Liverpool should not sell these two players before finding a replacement. Although Liverpool did not win the Champions League and Premier League titles this season, their performances were very consistent. Let's see how Liverpool's management decides.