There is a possibility that he will be sold and there is a possibility that he will not, if Mohammed Salah is sold to Saudi Arabia, Liverpool will lose their goalscoring machine because currently Salah is a very important player for Liverpool, while the current depth of Liverpool's squad has no one who can replace Salah's role. If Liverpool sell him in the midst of their struggle to win the Premier League and European League titles, they will experience difficulties, but if Liverpool has bought a replacement for Salah like Mbappe then it is certain that Liverpool losing Salah will be fine.
As far as I know, Mohammed Salah is not yet interested in going to Saudi Arabia even though the Saudi Arabian club is willing to sign him at a high price because he still wants to be in the European league and compete there. In my opinion, M. Salah is not too old to compete in the European league, and that is certain european players will consider going to Saudi Arabia perhaps when they are 35 years or older and Salah has not yet reached that age.
Yes, they’ll be loosing their goal poacher but with Kylian, I think Salah’s departure wouldn’t much be felt and that’s one credit. Salah might not be interested yet but I think winning the league title will be a perfect sign out for him especially once the fee from the Saudi club is increased. Salah is still fit but I feel it’s pretty better to leave when the ovations are loudest than bowing out with a bad season.
Of course if Mohammed Salah leaves and is replace by Kylian Mbappe it won't be a big problem for Liverpool but unfortunately there are many clubs who want Mbappe such as Real Madrid, Manchester City, Liverpool, Arsenal so at least Liverpool must reach a definite agreement before taking step to sell Salah because it is feared that the dream of recruiting Mbappe will not come true.