Actually at least in my case if I could get whole subnets opted out then I could move hosts that were on other nets that will be affected into the space, but since most folks don't have their own subnets that doesn't seem like much of a general solution. With regard to the issue of nats. I would strongly encourage anyone thinking of deploying one to seriously reconsider.
Somebody has to maintain the access list.
However, the use of NAT is a complex road to go down. It is clear that the arm of criticism cannot replace the criticism of arms.