The aim seems to be to return to something like the 1998 Adana agreement, which involved Syria undertaking to prevent PKK operating in its territory, which Turkey saw as a significant threat. Turkey would have limited rights of incursion, for example in response to attacks, but would not occupy Syrian territory. It obviously depends on Syria regaining control of its territory. It would end the threat of Turkish occupation of swathes of Syria, while giving Turkey something to show in respect of what Russia recognises as its "legitimate security concerns". Syria regains its territory, the Kurds are safe from attack though don't become an autonomous area, which is the thing that Turkey seems most bothered by.
It's not Trump's master plan, and I am not suggesting it is. What I'm saying is that he has been clear for several years that he wants to withdraw, but other forces within the US are keen to prevent this - though the idea that their motivation is concern for the Syrian people is laughable. The Russian approach appears to be to stabilise the area by achieving the return of Syrian areas to Syria while also reaching agreement with Turkey on not continuing its plans for annexation. That seems vastly preferable, to me. Ending conflict is also clearly required before refugees are able to return, leaving aside Turkey's barking proposal to forcibly resettle them in a strip of Syria occupied by Turkey.
I see the US-Turkey "ceasefire" arrangement runs until the day of the forthcoming scheduled meeting between Erdogan and Putin.