good post and a good thought.
I think it would be interesting if they introduced the new lead as someone from Arjun's past. Someone he may have know before Roshni or even after Roshni. Or simply someone he knew at one time in the past life.I will miss Sana as Riya, and also the character of Riya, but I am sure CVs won't dissapoint us. They have know for a while about Sana's health so they must have planned things accordingly. Let's give them a chance.