Not even near the end, IMHO. As Winston Churchill once said:
"Now this is not the end. It is not even the beginning of the end. But it is, perhaps, the end of the beginning."
Rebellion in their moderate form and ISIL is militarily defeated. That said, their future fight will become scarce, a guerrilla like struggle, especially for ISIL, and that will gradually die out, in decades to come. But never completely.
The major and real struggle (war conflict) will be with more resilient threat and adversaries - basically: Turkish backed militia and Turkish regulars, second, Kurdish separatist forces, supported by US coalition and third, Israel preemptive actions against any threat which suit them and the US.
Those adversaries will not be expelled militarily - not by the Syria, even not with larger, true intervention and support by Syrian allies (in first place, by Russia). But, in that case, if US and Russia for example, become involved in full and open war - we all know what will be outcome...
For the fourth adversary, Salafi/Wahhabi and Al-Qaeda like/linked groups - they will be defeated gradually, but as with ISIL, that threat will never be eradicated.
And, that is not just Syrian problem - those Islamic fundamentalist, their insurgencies and terror groups, is much more complex and deeper problem, which can not be resolved without real and inner self cleanup, by all major Islamic religious groups. And that will not be the case in the foreseen future. If ever.
As matter of fact, with more and more liberal and rich Christian West (globally North), social difference between them and more and more rigid Islamic world will be bigger and bigger. And on top of that, booming population with less and less resources, may lead to true War between civilization and religions. To the some point, one can see Syrian Civil War as introduction and precursor of this struggle between rich North and poor South, liberal West and rigid East.
So, what is only hope and possibility for Syria to get rid of those occupying forces, is diplomatic solution. But not before the US and Russia, find common ground or even become allies again. And then they together may persuade Turkey to abandon Ottoman Empire restoration.
Summary - after campaign in South, and maybe limited operation in the Idlib (to regain Latakia, highway M5 and Idlib countryside), things will cool down - if the US-Russia relation, remain in frozen Cold war like status quo. If there will be open conflict between US/Israel vs Iran, then things can become more bloodier, but the major factor and then, will be US-Russia relation.