I guess that the main point is that, since WoL, there haven't been any new attractions that didn't come at the cost of closing an old one. I could be dead wrong but it seems that Disney has forgotten that people like rides about the future or of transportation. Horizons was great but just needed some refurbishment. I would add a new World of Motion ride themed to "Highways of the Future", with a fun twist on the old Tex Avery cartoons (yes, I've mentioned that before). There are so many ways to make Futureworld work. Worried about theme/immersion? Go contemporary or use water fountains, trees, and settings to what we think it could be like. Either use flashback to what people thought the future would be like or set the entire land to what we want to see in the future (ex. Clean, natural, etc..)
Yes, add a few rides to the World Showcase as well. Not every pavilion needs one but throw a few in there for Italy, Germany, and Canada. Basically, create rides at periodic spots to give the crowds something to move through.