Right now, they are showing Robbie struggle between attraction towards Kiran vs loyalty towards Kasturi. With no hope of Kasturi recovering, he will be 'advised' by everybody to move on with his life and so that might lead to a more solid attraction towards Kiran.
I think the chances of Kiran actually being Kasturi are very low. I think the creatives will rather show it as Kasturi getting more and more mad and unstable in her insecurity. So much so that she will have to be shifted to a mental facility! And then they will show Kiran as being around to pacify and help Robbie through that hard time and that leading to full-fledged romance between them.
Next, if and when KP-SA differences are settled, then the creatives will bring back a fully-recovered Kasturi back into the show and then restart RoKa romance but this time with a triangle Kasturi-Robbie-Kiran till they ease out the Kiran character!
I feel this is what will happen.