I too feel Sai will not get Vinu by the end of this track and it will be heartbreaking for her. Aaba already told her a son has the right to live with his mother but she has to intezaar. That word intezaar itself is a hint from the writers that Sai has to wait for long long time to get her right. She may allow Vinayak to live with his so called *mumma* but I'm sure she won't give up on him no matter what. She'll still try to be a good Aai of Vinu.
Secondly, Virat has this impression in his mind about Pakhi that Pakhi is a mahaan woman who did so much for him and his family yet didn't get any happiness in return. I do feel this bhram is slowly breaking. He witnessed her 'mahaanta' when she refused to allow Vinu to call Sai choti mumma. He witnessed her 'mahaanta' yet again when Pakhi called Sairat's son Vinayak as hers and Virat's son and literally talked like Sai Vinayak ki kuch nahi lagti. Virat was clearly annoyed with her words but is being patient with her because he is under this misconception that Sai will get Vinu only through Pakhi.
Vanku claimed in his live that bahut jald Sai aur Virat ek honge. If what he said is even 1% true then Virat ke sabr ka baand bahut jald tootne wala hai. The image of Pakhi being this perfect selfless mahaan woman is going to get destroyed soon and when that breaks he won't tolerate any shit of Pakhi anymore.
Sai definitely won't get her Vinu back by the end of this track but ab dekhna yeh hai ki will Pakhi win or lose? If the writers are indeed working on getting Sairat reunited then Pakhi has to lose Virat in the sense she'll lose his trust and commitment forever.
If Sai won't get Vinu back Pakhi too has to lose Virat's trust then only the story will move forward otherwise it will be back to square one.