Under the old policy, things would revert back to what you owned previously. The new policy combines the subscription with an upgrade plan.
I think the sticking point for you is the wording that indicates that you only get to keep the upgrades for the extensions you own. I had to read this carefully the first time as well.
So as I understand it:
If you owned Sculptor v2, subscribed and started using Sculptor v3, unsubscribed, you would walk away with Sculptor v3
If you used Sculptor v3 under the subscription plan but had not previously purchased Sculptor, and unsubscribed, you would walk away with nothing but the work you had done with Sculptor.