I have been following Kasamh se for sometime. From all I know about Jai., he is not a person who does not like to take on responsibilities. He has his sisters family with him and he himself was taking care of many orphan kids.
It was kind of odd when many of the fanfic thought the same thing. From tonight it is clear that they have accepted each other very much, so if Bani gets pregnant I am sure Jai is going to be thrilled.
Something that can happen is Bani might know the Raaz and move away from him. Jai having fallen for her totally will protect her , and would like to get back her into his life very much when he knows that she is pregnant.
Let me know your thoughts