Movie World has turned more towards DC as an influence recently. Not saying a Looney Tunes attraction is impossible, but if it is to be a kids attraction, it should be something that is current. While the comics are outdated as well, the new movies are made with the same recognisable characters, characters that the children will relate with, even if they are too young to have seen the movies, there is a whole market for selling related products to kids who are too young to watch the movie.
No matter how nostalgic a Looney Tunes Attraction would be, the only reason for building one is to fit with the theme of the area. MW is more likely to theme it to something modern, that the general audience (in this case kids) will relate with.
I wonder if kids these days would know who Pepe le Pew is?