What do we learn from "b'Tum'asech Zimah"?
Rashi: You will be eradicated via the Tum'ah of your Zimah.
Radak: You are still in your Tum'ah, i.e. Zimah.
Malbim: In her Tum'ah is found Zimah, i.e. deep counsel of Zenus, which will not depart via fire. I explained above (16:43) that Zimah is fixed via fire, like it says about Zenus with one's mother-in-law "Zimah Hi ba'Esh Yisrofu Oso v'Es'hen" (Vayikra 20:14).
How was Hashem Metaher her?
Rashi: He rebuked her via the Nevi'im - However, you did not become Tahor (Radak - you did not heed Me).
When can she become Tahor?
Radak: After she will receive the punishment. This is like "Hashmen Lev ha'Am ha'Zeh" (Yeshayah 6:10), like I explained there.
Malbim: Since I was Metaher you and you did not become Tahor, I know that you will not become Tahor until I put My anger on you, to punish you with captivity, exile and scattering.