This idea that the Khans can be replaced or replicated is such a foolish one. That's now how this works. Back when Dilip Kumar, Raj Kapoor and Dev Anand were ruling the roost, each of them superstars,it took decades for there to be an equivalent trimurvirate. In fact, not until the Khans was there another threesome like them.
Of course there will be individual superstars and maybe even a duopoly in the near future. But another group of 3 at the very top of Bollywood for years and years and years? Yeah, that's not happening anytime soon.
1