what kind of career would she have had?

I don't think she was especially talented but I do think she seemed down to earth, unaffected and pretty sweet. I think her acting career would've been short but that she would've been OK with that.
I wonder more if she might've been Roman Polanski's salvation since he was already wrestling with his demons from his years of growing up in the Krakow Ghetto and she seemed like a ray of sunshine for him.
Or maybe they just would've divorced in a few years like everyone else in Hollywood..
We'll never know.

I wonder about this too.
If she had not been murdered would she have been famous for her acting?
My guess is no.

She was extraordinarily pretty, but nothing I've seen her in has said 'star' to me. I guess she's have worked steadily until she hit 'that age' when roles become harder to come by for women.