I may belong to minority here but I am not at all worried due to Raima's entry. Reasons-
1)Rohit and Sonakshi are leads of the show and viewers are invested in their story. So makers won't take the risk of giving more screenspace to Rohit and her ex.
2) Raima's character will be played by a not so popular actress. So she won't bring the baggage of her fans who will pester CVS to pair her with Rohit or give more ss.
3) ITV viewers like drama and a simple love story will become monotonous unless they add some spice to it. The more hurdles a couple face in the path of their union, the more appealing their union becomes . As they have already started Raima track,now her death will make Rohit guilty for lifetime. She has to recover and get settled in her life to free Rohit from his guilt and move on in his life. Otherwise even after a successful operation he will keep getting reminded of that slap. Raima returning and Rohit choosing Sonakshi over Raima will prove that Rohit actually loves Sonakshi and she was not chosen to fill the gap of Raima's place in Rohit's life
4) Suppose Raima turns negative and forces or blackmails Rohit to marry her, will the Sippys agree so easily? Sippys have been shown to be educated and smart people. They have accepted Sonakshi as Rohit's life partner because they like her as a person. I have a feeling that if such a situation arises they will not let Raima fulfill her evil intentions. And Sonakshi herself is no abla naari. Also she has Netra to guide her.
5) And last but not the least, Sonakshi's shraap to Rohit that he will never get Raimaš Parvati kaa shraap CVS kabhi fail nahin hone Dengeš³