I read the "fantastic 1981 novel", too, and you know what? It wasn't very good. It had a lot of really interesting world-building and some cool ideas, but the characters were flat and the central mystery was terrible. Despite common wisdom, the book is not always better than the movie.

I mean, given that Disney wasn't doing anything new with Roger Rabbit, I'm glad he got the rights back. But I think part of the reason that very little new material got produced is that the first movie was kind of lightning in a bottle. It's possible other production companies would have had to be involved to get something new done, depending on how the rights were parceled out. (We're all talking about Disney here because that's who Doctorow focused on, but it was a co-production with Spielberg's Amblin Entertainment.) And I think you're right that he's unlikely to have the rights to do a sequel that's too close to the original.

> the characters were flat

Yeah, isn't that the central gag of the movie though?