No, it's not confusion over that. It's debate over which block they'll be internationally. One person believes they'll all be changed and we'll essentially go back to how things were before regulation marks, and others believe it'll remain consistent with Japan.
Then there wouldn't be a point in the marks in the first place, or at the very least we would have started with A if synced legality weren't a goal.
Also, nobody has said that anything is impossible except you, which is what people are taking issue with. You're free to have your opinion on the...
And yes, also Shining Fates. Japan does it frequently as well. It's part of the reason the marks exist in the first place. Also, if staying synced with Japan weren't part of the plan we wouldn't have started with D.
It's not "literally impossible." Mixing regulation marks in a set has already been done. Legality isn't set-based anymore. Need I remind you of the fact that the Trainer's Toolkit this year came with two promos that rotated weeks after the release?