I think it's such as shame the legal folks and egos on all sides got in the way. Roger Rabbit was a great movie - one of those that appeals differently to several ages. As a 'kids cartoon' it holds up as a fun romp but the Chinatownesque plot is also engaging for adults.
The character had a ton of potential and was a natural theme park fit. It's such as shame we never saw more of him. Roger and his toon world would have been a great fit at DHS or Hollywoodland but I doubt we'll see his resurgence unless Iger and co decide their next acquisition is Amblin!
Don't know if it was partly a PR move, but Spielberg's falling out with Disney was during Eisner's time and I'm not sure there's much bad blood anymore.
Certainly would be awesome if they collaborated on another successful project together, and definitely would be awesome if we could get more Rabbit in the parks and another film.