Since when is Mandzukic an SS?
SSs score like 10-13 league goals/season, even if they are tall like Amauri, Matri and Vucinic and can be used tactically as a target man, since they cannot score by themselves +15 league goals/season, they are complementary to scoring purposes. In Italy scoring is a much harder issue than it is in Spain, so a player that scores just 10-12 goals in Spain, will do even worse in Italy.
Higuain who is a finisher scores in Italy 17-18/season, whilst in Spain was having +20league/season.
+20league goals/season are numbers for the top finishers like Cavani.
Sometimes, rare talents like DP, Zlatan and Tevez appear that can both create and finish with ease. These talents are unique and irreplacable.
This double role is better replaced by two specialised player, one that is specialized at creating and the other that is specialized at finishing.
With Dybala we have covered the creative part, Morata is bound to cover the finishing part, Mandzukic is somewhere in the middle, a hybrid if you like.
Good overall, not very good at smth though, usefull tool for a coach like Allegri, who is a great at rotating players considering their role, fitness and synergy with co-players.
From the finisher-only-POV, Mandzukic is a mediocre finisher for Tevez-less Juve standards, but overall he is 100% Juve material, it would be unfair to him to ignore his other ball skills.
Hopefully, we will use a trident and benefit from everyone's skills!
A two player forward line with Dybala and Mandzukic, would be lacking at finishing. Manzukic and Morata would be lacking at asisting/creating.
Tevez was a player, that could create, assist and finish +15goals, Dybala only scored 3 and 5 years/season with Palermo,before his one hit wonder season,
he will need a prolific finsher of +15goals besides him, to complement him.
With Berardi and Zaza coming, we wont have to worry about the future, just next year.
Further investments should be reserved if Morata and the young ones fail to become +15 league goals/season class of finishers.
If we use the trident, we will need 2 SS-ish players and a CF, Morata and Manzukic could both handle that role and could also help as a SS, with Dybala providing the main supporting role.