For US properties the list would probably be shorter if they just listed participating properties instead of properties opting out.
I'm surprised the SF Hiltons didn't opt out like they always do. Maybe the Parc 55 decided to not opt out of promos and they have some competition now.
All the properties I am booked at have opted out except for the Palmer House and the Fashion District Hilton. I have expensive stays at the Seattle Hilton and the Boston Back Bay Hilton booked and since it doesn't look like I will need the breakfast, I am seriously considering moving those stays to SPG's.