It will only take Jurgen Klopp a moment to reorganize Liverpool if Mane does leave. Luis Diaz is one example of Jurgen Klopp's greatness in managing positions. In my opinion, the heart of Liverpool's attack was not entirely on Sadio Mane, but Thiago and assisted by 2 full-backs T. Arnold and A. Robertson.
Liverpool doesn't have a good center forward except Sadio Mane, Diogo Jota and Roberto Firmino had bad performance as a center forward substitution. Though Luiz Diaz can play in the center forward, but he's better play on the Left Wing and Salah always on the Right Wing. Liverpool need to think twice to not let Mane leave their club, because their rival e.g. Manchester City already got a good striker which is Haaland.
Darwin Nunez from Benfica if he really replaces Mane's position at Liverpool will experience less impressive statistics in formation, because Mane is the heart of Liverpool's game in concocting attacks, losing Mane could make Liverpool look for implants for the squad, so Liverpool must be careful about that.
Darwin Nunez is a potential player, he could replace Mane's position since he's also a center forward. But the bad thing is his performance isn't stable and there's a swing, he can play very good and play very bad at the same time.
At the moment Liverpool could be pretty active throughout the summer as I expect several players to leave. So it’s likely they will sign a few replacements. Sadio Mane has sighted his desire for a new challenge as the reason behind wanting to leave and Bayern Munich immediately emerged as the most likely destination. Completing the signing of Darwin Nunez from Benfica providing he transfers his red-hot form in Portugal to the Premier League will help soften the blow of losing Mane. Now we must hope that Nunez is the right man to take Mane's place in the front line.