Salah and Mane are definitely important figures in Liverpool, and if they probably leaves. I bet Liverpool performance will surely drop next season. Am quite sure the team won't want to lost two of their best players at a time, if Mane choose to depart from the club, the management will do anything within their capacity to ensure they retain Salah. However, after Bayern Munich lost their key player Lewandowski. They basically need an experienced player like Mane to replace him.
Sadio Mane and Salah are good pairs in the team, they understand each other and have a very good teamwork that is perfectly going on. But the team are mute to listen to the demands of the both players, Mane and Salah asking for an increase in their salary, that's not too much for the board to handle. For sure, Mane is leaving Liverpool to face a new challenge while Salah might still be in the team because definitely, Liverpool board will increase his salary while Mane mind is already made up and he is ready to leave the team.
According to news circulating Mane asked for a significant salary increase and also, for now Salah did not demand a salary increase and chose to stay. But if over time his salary is not increased then I'm sure Salah will be ready to leave too, instead of raising all salaries which will be a financial burden then I personally prefer to let them go and Liverpool can get other players like Diaz. I just don't believe Liverpool can afford the high fees, rather than later making a regeneration that doesn't go well, it would be better to do it early.