To take your scenario one step further . . . OK, you can't get BOG on Saturday, but you can get it on Wednesday. What happens if you can't get admission to MK on Wednesday, but you can get it on Friday, but there's no BOG for Friday? Or you manage to get MK and BOG on the same day, but there aren't any good FP+ except on Thursday at MK? If this scenario works the way people are speculating, you need to get three sets of stars to align - FP+, ADRs, and now ability to access a particular park on a specific day - to make your plans. That could make things a lot more interesting for the super planners, especially those that like to tweak their plans a lot.
Since I buy a Florida Resident AP, I'm used to having the different admission dates to consider when I buy the pass, and I don't make a lot of advance plans for my trips because I visit so often. But I can see that there could be a lot of potential headaches for a lot of people, depending on how the plan is implemented.