I have only seen this hate from sites where people blame KJo for nepotism and then go watch those movies over and over again.
In FB/Twitter there aren't people who want Khans to be finished.
If Khans makes good movies, no one will want them to leave, but if the continue to (mostly) make bad movies, of course people will get fed up. I know many people who would rather watch a Khan movie but are only getting good product from elsewhere.
In 2017 and 2018, we have gotten Raees, Tubelight, JHMS, TZH and Race 3 from Khans. 3 are legitimately bad movies, Raees is a mess, and TZH is good but not as good as Padmaavat or Sanju.
If they are to prolong their career, good movies are a must.