If Liverpool loses to Salah and Mane together, their attack will be completely broken. Although Liverpool is a stable team, but still they rely heavily on these two players. So I don't think they will decide to sell these two players together. Despite the decision to sell Sadio Mane, Salah will probably be seen in Liverpool's jersey for a few more seasons.
Lewandowski may not be interested to be a part of the Bayern Munich squad. And so the Munich management is trying to bring in Sadio Mane to replace Lewandowski. Munich management has enough money, but even if Leandowski leaves the team, maybe Munich will be able to take on the star striker.
I think Sadio Mane will leave Liverpool this season and join another team. Maybe Mohammed Salah will choose to stay with Liverpool this season and the next season because with Liverpool his name has shined even more this season or in the previous season. I think Liverpool will be quite active in the transfer market this season because they will look for a player who can replace Sadio Mane.