Anyways... Back on topic.
I do agree with Red on the grounds that it wouldnt effect the dynamic too much as Sally/NICOLE/Tails could easily cover what Rotor brings to the table. I also agree with Red that his death would need to be impactful to have any effect to the story itself, it cant be some throwaway bit or something minor. Everything has to have a reason and it would have to have meaning behind it
However there's something that needs to be mentioned if Rotor were to perish: the psychological impact of his death. Even if he were to go mid-mission, tragically, etc. it's going to damper morale of the Freedom Fighters in a major way. The fact that Rotor grew up with them and his death would cause a major impact to the mental well-being of his friends. How would they handle it? Would they be overly cautious during their next mission(s)? How would everyone cope? If Robotnik was the one to kill Rotor does he use this to his advantage? There's a few questions that would need to be answered.
TBH, though, why would you want to kill Rotor? I love the guy, and I wish he was given more spotlight.
Him and Bunnie needed more spotlight in Season 2. There's something more to Rotor that could be explored.