The sudden and unprecedented advance of Syrian regime forces into northeastern Aleppo in recent days seems to mark the collapse of the anti-Asad rebel groups that have been holding out there, especially Jabhat Fatah al-Sham (formerly Jabhat al-Nusra). A victory by the regime and its allies is likely to come at great cost; eastern Aleppo has already suffered horribly from bombing and the systematic targeting of hospitals. And while Syrian forces have been de facto cooperating with the Kurdish YPG and Turkish backed elements, he very different end games envisioned by those three elements may lead to new conflicts.
Once the regime recovers the ruins of this once great city, it will control the major cities of Syria, the "useful Syria" it considers sufficient to assure its survival. It will have recovered Aleppo through the unchallenged and unrestrained application of Syrian and Soviet air power. The chimaera of a no-fly zone is long since moot, rendered so by direct Russian intervention. There will be plenty of guilt to go around for the destruction of a great city; the West is hardly free of guilt, but the Asad regime and its Russian and other allies have the largest amount of blood on their hands.