And none of that will prevent someone from using the new AP material. Rage of Elements was released in July (I think) and it already reflects the Remaster material without breaking compatibility. Currently published AP material seems to reflect the new material (e.g. new stat blocks drop ability scores and just list the modifiers) while still referencing previously published books, such as using stat blocks from Bestiary 1, 2, and 3. I’m not sure where you sit on the 2024 D&D compatibility debate but this is basically the same situation. It won’t matter if people want to continue using alignment, magic missile, or OGL monsters since mechanically it’s just going to be like you homebrewed them in. Just like it won’t matter if you had a 2014 warlock playing with a 2024 paladin and a Tales of the Valiant fighter.