Why would the show end?

If Barun quits and people think that nobody else can play Arnav (I for one am not one of those people), then I would rather the writers find a way to exit the character and move on. It doesn't have to be a new lead for Khushi immediately but we could see a track where Khushi finds herself penniless and with the responsibility of the entire Raizada and Gupta family. She uses Arnav's will to start her new business and creates a new empire for herself. While doing all this, her character undergoes a transformation as well - she is more focused and serious now. She still cares about the people she loves but she is now more street smart and is able to think with her head rather than her heart in most situations.

Just a thought - there are other actors on the show who work very hard and it would be very unfair for everyone to be out of a job because on actor quit, don't you think?