I read it differently, because all policies are annual, and needed annual renewal (with new premiums). So my interpretation is that if you currently have a policy, it will only last until renewal date - but they will try and find alternatives, and indeed will be required to for those with existing conditions.....
As an aside up until a few days ago you could still get quotes , and I discovered that you could be living in the same road and have different quotes on the same dog, but one postcode cost over £100 more !