Despite the very long and costly effort to capture Aleppo, which was destroyed in the process; and despite the capture of large amounts of territory in the east because the American-led coalition has defeated ISIL there, a lot of rebels still hold more important territory in western Syria.
The rebels might yet infiltrate Aleppo to make it a further drain on blood and treasure to hold for the Assad regime. Especially if Turkey doesn't want to throw a complete victory to Iran and Russia.
And there is a lot of territory in the east and people not likely to submit to Assad's return. People who may have the support of America and our coalition.
In addition, rebels backed by America still hold parts of the south.
And other rebels have pockets in the western arc from the Jordanian and Israeli borders up to the Turkish border.
My view is that given the massive casualties the Assad ground forces have endured, that there is more hope than reality in government (and Russian and Iranian) claims that the war is won.
If all those factors break Assad's way, then yes the war is on the road to being "won" by the strategy of bombarding, gassing, and starving all opposition into submission or flight.
As Strategypage notes:
Russia and Iran have already come out and declared their support for the Assads as the legitimate government of Syria and with ISIL gone the rebellion is being declared over. Neither statement is true. There are many Syrian rebels who have little or nothing to do with Islamic terrorism (like the Kurds and FSA). The rebellion is very much alive.
Do foreign enemies of Assad believe Assad has won? If so, it might be a self-fulfilling wish if they cut support to rebels as a result.
But if the rebels are willing and able to fight on, the war is not over.
And if the rebels fight on, how much longer will Assad's supporters go along with the death of their sons and the ruin of their fortunes to maintain Assad's rule when the threat of a bloody ISIL victory has been destroyed by America?