Originally, Chase was going to have Tony actually smother her with the pillow in S1, but the actress, knowing she had terminal illness (cancer?) asked him to keep her working as long as possible so he kept her in the show til she actually passed. This is why her role in S2 is minor, compared to S1…she wasn’t intended to be there, plus she was sick.
Had she not passed, in S3 she was going to testify against Tony about the airline tickets (according to chase). Not sure if he’s mentioned other plot lines or how her character would’ve ended up.
Thinking back on it, it's actually amazing how Tony never steps foot in a court throughout the whole series. Would've been interesting to see him interacting with a judge and a prosecutor.