No one can doubt that Mbappe is a good player and he'd improve the squad of the Gunners but I don't think Arsenal needs such a player RN. He's got a self-centered mentality and I doubt he'd be able to fit in the team. What Arsenal needs is not just any kind of forward, but one who would be willing to share chances when he's not in a position to score, not a childish player who stops putting effort the moment he does not see the ball.
Its not that Mbappe would improve Arsenal, but he would improve just about any team in the world (except maybe Man City but I am pretty sure that Pep would fit him somehow). Having said that, there's literally 0 chance of him joining Arsenal as it would go against everything they do as a club and the most realistic scenario is that he ends in Real, either this season or the next (more likely)
In other news, I still can't believe that it looks like Brozovic is going to Saudi Arabia in the end, mainly because it might have a big impact on our (Croatian) national team as level of play in Saudi league is much lower and I am afraid that will affect his performace for national team. Too bad that Barcelona can't afford him at the moment...
Saudi Arabia league will soon be as competitive as Bundesliga or Ligue 1 if they continue recruiting players that way. They started with Cristiano Ronaldo and every day you hear about new name coming to play there. Mendy, De Gea, Neves, Koulibaly, Firmino, Kante, Niguez, fofana...are names that joined or will join Saudi Arabia league!
For Mbappe, I think it is random to think he will agree moving to Arsenal, this if we suppose that they have enough funds to bring him there.