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.
In Syria, the devastation from years of war is tragically evident. Buildings are ruined and burned out. The fighting is still progressing between government forces and elements of Daesh and al-Nusra. The violence has effected exurban neighborhoods and rural towns nearby. There is also substantial damage to Syria's industrial infrastructure, particularly in Aleppo. Anti-government forces occupied the extensive industrial zone and proceeded to loot the factories.
Millions of dollars worth of textile plastics, chemical and pharmaceutical firms were sold off. The electricity and water systems have been put entirely out of operation. More than half the country's hospitals, clinics, and health care centers have been damaged beyond repair. Rebuilding neighborhoods and housing stock on a large scale will be an enormous and costly challenge. Trump has placed a freeze on recovery funds even for the areas of Syria occupied by US troops. Resettlement of people will be an unfathomable task.