May be tough for Salman. But some other actor in the future will achieve it while enjoying his superstar status in the market. Just a waiting game to see if they're going to be from the current bunch of Varun or Ranveer or Tiger.
Holding back Ranbir solely because Brahmastra is extremely risky. If he succeeds there then nobody is stopping Ranbir from claiming the top spot.
So yes, who might earn that sort of market post Khans, Kumars & Devgns is interesting. In case of Hrithik though, more than Kangana, it is the media who is not supportive of him. Add to that his slow movie selection style... Let's see what Bollywood offers when seniors start to fade.