First of all, the idea of dropping David Warner was wrong. And secondly, in place of Warner they could have added another batsman, and not an all rounder like Mohammad Nabi, who is in very poor form.
I have complete different opinion than you: Warner deserves a break. Mohammad Nabi's addition (just a couple strikes away from getting back the form) is a good move as he will add extra depth in middle order and will bowl decently in middle overs.
I don't know why they are not giving enough chances to Jason Roy and Mujeeb Ur Rahman, despite the poor performances from their regular players.
I agree that Jason Roy should be considered in place of Warner but limited overseas slots a concern. Mujeeb may not find a chance as Rashid Khan and Mohammad Nabi are already taking care of spin bowling department well enough.
Anyway, half of the IPL is over and I don't think that SRH will be able to qualify for the playoffs with such a squad.
With new captaincy, I guess they may keep trying to push so that to rank top 4 in table. I guess chances are still there for all 8 teams at least mathematically.