Idk what the hell Turkey is afraid of now that they got so deep into this mess, it is either do it and seal the deal by crushing the PKK or retreat from Syria in disgrace
Turkey needs to solve the kurdish problem quickly because Israel is expanding the land it annexes; the more Turkey waits on the kurdish issue, the more Israel will annex lands and the more weaker will the new govt position be
There is already a seriously growing discontent within SNA due to Turkey's hesitation and the YPG-US-Israel axis is using it to its benefit
Honestly, at this point, I would tell Russia to keep its bases in return to aiding the new Syrian govt to take back the lands Israel took within a short time frame of a month. As far as I know, Russia is playing all the cards it has to keep the bases it wants in Syria