I think IF they go for a IP, it will be more likely to be a large IP such as a TV channel or a big brand, just like Nickelodeon which has no end of shows/films that can easierly be turned into rides or shows, and can always be added to and changed over time, and Thomas Land, which has no end of characters, scenes, etc, which once again can be turned into rides/shows.
If you pick one IP e.g Wallace and Gromit, you would struggle to have a whole area to that one IP, but like at Blackpool it works fine on one ride.
Finally the area/rides have got to appear to young and older children, like Nick Land does.
So I'm thinking we will see a big and famous Kids TV channel such as CBBC or CITV (I would say Cartoon Network, but Drayton also have that!), both of which have no end of TV shows, that appeal to young and old children.