I think Liverpool are getting the players they deserve for Mane's departure, although Nunez will have to adapt first. But for a young player like him who has more motivation it looks like it will go well. When he plays well and as expected, I think Liverpool will easily move on from a Mane who we know he has contributed a lot to this club.
To pay 75 Million € (it can go up to 100 Million € if all bonus targets are met) for such a young player that has not really shown if he can really deliver his performances in the best European Leagues is obviously a very big risk. I expect that Liverpool will not be as strong as they were at the end of last season when the new season starts. They have lost Mane, which is an absolute world class player that was used to play in the english premier league and he was a very important part of the team for a few years already. Even if Nunez is adapting very fast and is able to deliver everything that people are expecting from him, i don't think that he can fully replace Mane in the first matches. It will take some weeks to do that.
It is a risk taken by Liverpool and I think it is a calculated risk. Now we just have to wait and see if this pays off or is it just going to be another case of an overrated player being bought by a top club for an excessive amount of money.
I think this is going to pay off very well for Liverpool if he can start early and start scoring. But I also think that it is going to take a little bit of time for him to get settled in the team. After all, I just hope that he does not feel too much pressure because of all the expectations on him, I hope he plays his natural football. It is better for a player if he performs freely. If this player can start early, he will have a big impact on Liverpool winning the league title.