Maybe a hybrid concept where it could technically be based on both? But yea, this new movie is gonna be a huge hit, (and may only be the first of a new trilogy,) so they're gonna wanna have this tie into it for sure.
EDIT: Fun Fact - Mary Poppins Returns will have the longest gap between live-action film sequels in history at 54 years.
I wonder if a Pooh/Christopher Robin concept was ever on the table, what with the movie and UK tie in it must have been discussed. I know we alreadt have a Pooh ride but something more Christopher Robin orientated could have been a fun idea too.