Forgive me (again)
My understanding of the situation is that the CAA will issue the first ARC with the non-expiring EASA C of A.
After that, if you sign-up with a CAMO in a controlled environment and agree with them the limits of the maintenance, then the costs are reduced. You 'may' also have the ARC extended for up to 2 years, so we have the current situation of Star-Annual-Annual-Star.
In the 'Uncontrolled Environment' where the owner has no agreement with a CAMO, he is not able to raise the work pack and each time he approaches an MO he effectively funds a Star Annual. The costs in this option are significantly higher than in the Controlled case.
Worse, because it becomes prohibitively expensive to change CAMO, they have you by the short and curlies. They can also remove any or all of your rights to carry out pilot maintenance, if they so wish.
This will lead to owners carrying out their own maintenance or getting someone else to help out, and not recording it, in the hope or expectation that no-one will notice.
One of the great joys of looking at EASA legislation is the way that it encourages owners to find ways around the legislation, rather than complying with it. Hardly something that was planned.
Now, this may be different in Euroland, but we are being driven down the preferred CAA view.