As a half Croat: sorry, won't happen. Croatia's economy is tourism dominated and will stay that way. There is a bit of agriculture and industry (especially shipbuilding), but nowhere enough to compete with heavyweights such as Germany.
For those out of the loop: the Balkans have historically suffered from brain drain - first during the Yugoslavia era where many fled/emigrated from realcommunism, then during the wars for obvious reasons, and now simply because Germany and other EU nations pay way better and those who don't find work in tourism find it elsewhere in Europe instead. Good luck finding a nurse on the Balkans... Germany has to recruit from the Philippines meanwhile.
The fact that Croatian (and other Balkan countries') politics are extremely corrupt doesn't help much either, it's really sad.
Regarding Southern Italy: similar situation re/ brain drain, plus the added complexity of having to deal with the Mafiya.
Regarding Turkey: Turkey already is an economic powerhorse and a regional hard-power leader - the early Erdogan years showed what Turkey is capable of. Unfortunately Erdogan turned into Erdolf and investors are pretty much shying away from Turkey as a result of the instability, not to mention that Turkey is directly adjacent to the Syria cluster-fuck.