One can't predict which story and opportunity goes to which actress or actor. Filmmakers keep one star in mind when they ready the story but it goes to another actor for various reasons ranging from lack of interest, dates problems, remuneration and busy schedules.
Everyone knows it is becoming extremely difficult for the Tollywood filmmakers to find heroines opposite top stars. The preferred heroines may not be available when the film goes to regular shoot and the available heroines may not show interest. Under these circumstances, other heroines get that golden opportunity.
Prabhas' craze increased tremendously after Bahubali and while the makers planned to cast various heroines opposite him in Salaar, the golden opportunity unexpectedly went to Shruti Haasan. She is now making full use of it.
Balakrishna-Boyapati Srinu finalized Malayalam beauty Prayaga Martin as the heroine. Later the name of Sayyesha Saigal did rounds but from nowhere Pragya Jaiswal became the heroine.
Actresses dream of romancing Power Star Pawan Kalyan. Nidhi Agerwal became the heroine in Pawan's project with Krish. The makers considered various Bollywood heroines but Nidhi got the golden opportunity.
Many heroines’ names did rounds opposite Ram Charan in Chiranjeevi's Acharya. However, the makers finalized Pooja Hegde as his love interest.