In Italy, either the Etruscans would retain power, or be overthrown by the Latins or Samnites. Alternately, a League of Hellenic city-states led by either Taras/Tarentum or Syracuse in Sicily could colonize the north. From the north, Celtic confederations such as the Boii, Senones or Insubres may pour down through Etruria and Umbria. Another scenario could involve the expansion west of either Macedonia or Epirus may be successful.
Unless a strong expansionistic state with a growing population catches up with them first, the Gauls could coalesce into larger state-level societies. They have a semi-unified religion and common law. They have a complex road system, coinage, sophisticated agriculture, and possess a wealth of metal ores. And trade with the Greek colonies on the southern coast as well as those whom travel to the Celtic lands via the Danube could enhance this process.
Either the Punic colonies and their native Iberian allies come to dominate the peninsula, or they will be overtaken by the Celtiberians in the north, or the Lusitanni in the west.
The most likely powerhouses of the Balkans may be the Kingdom of Macedon, the Celtic-led Scordisci confederation, or the unified kingdom of the Getai (Dacians) whom follow a proto-monotheist cult based on the teachings of Zalmoxis.
Unless Carthage can become more than a commercial empire, they may end up being overrun by the semi-nomadic Numidians in the west of North Africa.