I'm not sure what you mean. You'd be able to use the 2014 MM or the 2024 MM for the statblocks. It won't matter which. I mean... I'm sure that if you ran the same fight with one or the other, they wouldn't GO 100% exactly the same but the point is, you could play it either way and it would work without any conversion.
It'll be the same for the characters. Again, you could play it with 2024 PHB characters or 2014 PHB characters (or a mix of both). People wouldn't be doing the exact same thing on every turn as they would the other way, but again, it would still work.
So it doesn't matter whether it counts as a 2014+ book or a -2024 book. It's the same either way.
EDIT: I see that this has been more than discussed already. Ignore me (I mean, not literally, but don't mind me.)