Back to the original topic.... it's not that a Magicband specifically will be required, it's that some character M&Gs will only be FP+ enabled. Meaning if you do not book a FP+ for that character, you won't be able to see said character. There are not many (none at MK will be this way), as it'll be more common to have dual operations (such as TST is currently set up).
Everyone will have a FP+ option: on-site, off-site, Passholders, CMs... it's just prioritizing what you want to do. Not as big of a deal as I think people are thinking it would be.
So, if this is the case, then most of the issues that people were having in here about the meet and greets (placing people into categories - MagicBand v RFID Card, Passholder, etc. are null and void) - if all they are going to do is add more meet and greets to FP+, then the only issue will be if "meet and greet" FP+ and "attraction" FP+ will come out of the same "daily number" that you get - if your child really likes meet and greets, and you reserve three of them, then is that your daily usage gone? (no FP+ for Dumbo or Peter Pan?) And, for meet and greets, if the adults taking the children into the meet and greet are not going to interact with the character/get their picture taken, do they also have to use one of their daily allowance on basically supervising the child?