Looney Tunes, Nintendo, and Hanna-Barbara are all currently licences by Six Flags....I highly doubt that Warner Bros would give the Looney Tunes Anywhere else. Though I could see the other two relent.
I've always thought that Super-Mario would make a great theme park attraction, but why retheme toon Lagoon? Do-Right and Barges are both great attractions? There is a little room between Toon Lagoon and Jurassic Park, in what looks like a boneyard/Overflow Parking Area that could be used for a mini-land or an expansion to either land. There is also some space behind Seuss Landing as well, but it's not substantial enough for anything but a Seuss related expansion.