Marseille made a good move by bringing De Zerbi into their team before the 24/25 season started, last season Marseille only managed to finish in 8th position,
I agree it is a good decision to change Jean-Louis Gasset because he totally failed in the last season. Finish at 8th was a very bad position, Marseille should be in the top 3. Although De Zerbi isn't a coach who won many trophies but he has good quality. With a new coach, Marseille can have the hope to be more competitive in the next season. At least, Marseille can be in the top 5 again under De Zerbi management.
with the emergence of de Zerbi as the new coach it seems that PSG has a big threat, because Mbappe has already left PSG so that PSG's goal machine is reduced
I am not sure if Marseille can be a tough competitor for PSG to join the race for the title. Even if Mbappe has left PSG, there are still other strikers who can replace the position of Mbappe. Randal Kolo Muani and Gonçalo Ramos are top strikers, too. These strikers can make a lot of goals as well if PSG coach gives them the opportunity to be the main striker of PSG in the next season. Moreover, PSG is rumored to sign Osimhen, he is a striker with the same level as Mbappe.
Marseille has a big chance to be at the top, De Zerbi can maximize Aubameyang's form, which has started to fade due to age
Marseille can't rely on Aubameyang only if they want to finish the season in the top position. They must have good defenders and midfielders. You must realize that Marseille defense line and midfield line are weak. If the new coach doesn't improve the lines, I doubt if Marseille can compete for the titles with PSG and Monaco.