The conversation between Nora and Nurse Anne in the opening of Act 2 definitely foreshadows Nora's thoughts of either contemplating suicide or abandoning her family; however, at this point, we don't fully know which she is going to do.
We first see the foreshadowing that something terrible beyond being blackmailed is about to happen when Nurse warns Nora that if she goes out again in the horrible weather, she could catch cold, and Nora replies, "Well, worse than that might happen" (II). Next, we see it foreshadowed that Nora will soon no longer be with her children when she explains to Nurse Anne, "I shall not be able to be so much with them now as I was before" (II). We see the idea that Nora will abandon her children when Nora asks Nurse Anne if her children would forget Nora if she "went away altogether" (II).
Later in the Act, when Krogstad comes to speak with Nora, we see it foreshadowed in this conversation that Nora has not only contemplated running away from home, but doing something much worse, which appears to be suicide.