With the war still on and the gravity of damages in Syria it would be difficult for Syrian refugees to rebuild their country.
According to World Bank, a third of the housing stock in Syria has been destroyed by the war. Homes, companies, industries and many other industrial structures and centers have been damaged to a fault. Hospital and care centers have been burnt down. Electricity and the water system is no longer functioning. It would be tough to get everything back and running.
Extremist and anti government groups still occupy most of the industrial part of the country.
Many Syrian refugees have settled into several countries across Europe and a lot of them are not even willing to return to Syria.
To rebuild Syria will cost a lot and it would be hard to take it back to it's normal state.