DinoLast
Super Freak
I think Sarah Jane should be killed off sometime during 11's run to demonstrate that the Doctor's allies are genuinely risking their lives by siding with him as they became far too indestructible during the previous regime.
I think a shock of that magnitude would be a good way for Steven Moffat to show his way of doing things is not the same as the other person's and it would give the show a feeling of "anything can happen" instead of being so damn predictable.
I think that might be too risky for the BBC, seeing as she is the star of a show that is aimed at the youngest part of the Doctor Who audience.
I do understand where you are coming from though about Assistants getting killed off. I still remember when Adric died on Earthshock and the credits rolled showing his badge. I only ever saw that episode once when I was a child and I still remember it today.