I don't know how much of this analysis can be correct. But I feel with the present understanding this is what I feel. Dev is shown tying a daaga in the beginning in the temple with the prayer " Till he reaches her keep Nithya safe" that means once he reaches her, he will keep her safe.
Identity as Durga Thakur is difficult to maintain beyond a point. I mean lot of questions can come. Someone like Shekar can come up in future. Even real Durga's lover or Dr Dayal's relatives, friends. With Sakshi breathing down her neck, it will be literal struggle to keep up that identity.
Durga taking down witnesses , she cannot do it in open battle, it has to be done stealthily, even Dev managed to get 2 of the witnesses are in trouble and Divya is missing after reading RTI files. So Sakshi who is as contriving as Shakuni will keep quiet. Yes she planned, but if she is able to execute it as per plan then it is the failure of the script. It is taking Sakshi lightly. Just like in Divya Bagchi track , Sakshi cornered Durga this time closing all doors for her. If engagement was not announced even Rajnath was willing to listen to shut down cancer research project.
My take is this. Durga has given all tools to Dev to understand who she is and what is her mission.She is giving him a chance to prove himself to her. When she took Dev to Payal she took him to mandir before that. Scene which was not shown to us. Reason is the plan where Shaurya is concerned she will do, but for Dev to reach her, she needs divine help as he needs to reach her on time.
Now she is expecting blunder from Shaurya. Once he gives her that, she will put into force steps to prove Shaurya's blunder. He is gonna give her a perfect blunder. Suicide drama. Durga will be back in her elements and will put forth actions to prove that drama was done for a bet. Most probably she will cry like a abhala nari in the altar on how she has been jilted in the name of true love( guessing because Payal was forced to retract her statement and Goenka's made the world believe that to get married to Shaurya Payal feigned rape. So she will put the same insult and blame on Goenka boy)
Then it will be the issue of maan samman of parivaar. Dev will be asked to be Bali ka Bakra. Most probably by then Dev would have known who she is, but he will feign as Bali Ka Bakra and agree for marriage.
But the problem will happen instead of looking like a couple who are forced into marriage both Dev and Durga will find it difficult to hide their happiness. It will show on their face throughout marriage ceremony one way or other. Sakshi will take the subtle hints and the realization may dawn on her " Nithya". But by then she would have been Mrs Nithya Dev Goenka the surname Sakshi cannot take away from her.
Dayal Thakur's daughter can be contested at various levels, but Dev's wife cannot be contested if Dev had married her knowing who she is.
If it is like that I would love to see the look on faces of Sanjeeda and Simone. It will be too good to watch.