winning there would have made a big differenceYes, but as Kerney said the longer the war goes on the harder it becomes for Athens to fully integrate the Delian League. Even in OTL they did manage to establish themselves as the dominant power of the Delian League to some degree as they made all the decisions for the League, they controlled the League's treasury, and they even exorted taxes and tribute from their "allies".
I'd say that any POD prior to the Athenian defeat at Syracuse leaves Athens in a fairly good condition to fully centralize the Delian League into an Athenian Empire, whereas anything after the defeat at Syracuse seriously hampers their ability to do so. They can still do it after Syracuse (I'd say the war is still "winnable" for the Athenians up until the Battle of Arginusae), but they will have a much tougher time in doing so.
winning there would have made a big difference
no it actually would have been every good for them if they had won that cosndiridng Syracuse richesAvoiding the Syracuse Campaign would have been better.
Well Sparta’s dominance was destined to have a bad end for the specific set of rules of that city, with Athens in power as winner I am less sure someone can bring its hegemony to the end because Athens had a much more flexible laws and a bigger interest to rule and if the Athenians are able to keep themselves from exceeding in “persuading” the other cities from joining the Delian league I can see their dominance during at least until the rise of Philip of Macedonia (unless butterflies and Athenian control on Greece prevented that)Depends on how they win. If it's the 25+ some year war, I think someone does something like what Thebes does to Sparta otl to Athens fairly quickly.
If they win a less costly victory but somehow gain some humility, say because they need someone else's help to help them, they get better at integrating and things work.