Losing Saint Maximin will not have a big impact on Al Ahli because they also have other players who are no less good. Moreover, this player was also not very productive in scoring goals last season, he only scored 4 goals in 30 appearances, but yes, he was very helpful in providing assists. goals and helping his teammates, but no matter what, Al Ahli can't continue to depend on these players.
While Maximin may not be a big loss, not replacing him would be a big loss. I agree that he wasn't some amazing player that can't be replaced, they can spend some money to get someone even better, easily, like spending 20-30 million would easily make it possible for them to get someone better.
However, if we are talking about not replacing, like if they do not get anyone, which they haven't so far, I do not think that they are going to be good at all, whoever is left there, isn't as good as Maximin. So that means they should be start looking at some transfers if they know what they are doing, it would definitely benefit everyone. I am not saying that it is going to be easy to handle it all, it is going to take some time, but we could make it work some other way if we know what we are doing.
Al Ahli should be looking at older players at Europe, or maybe some young talent from Latin America, that could be cheaper honestly and could be very beneficial for them to get. In any case, they are not good like Al Hilal or Al Nassr if you ask me, they need to spend some money to get as better as those teams, and for that they need to spend some huge bucks to get some great players for their team.