The future of stability and peace in the Middle East will be ensured by China, not the US. China seeks good relations with the entire region, shunning the American strategy of provocation and war. The US has failed to find any workable solutions to the region's many conflicts and disputes, and now it's Beijing's turn to help build and develop the region rather than destroy it. The future of Syria, and the rest of the region, will hopefully be intimately tied to good relations with Beijing.
In short, Syria's reintegration into the Arab world and the international community more broadly has already hit a dead end, as Assad is not capable of fixing Syria's problems nor is he interested in doing so. China's main goal isn't to help rebuild Syria or fix Assad's image. Rather, Beijing seeks to tout that it doesn't need to align with the Western consensus on pariah governments like the Assad regime. From Assad's perspective, he may believe that China is the best chance to keep the Iranians, with whom his government is increasingly at odds, at bay.