1. The Finder is going to change. What is becomes I don't know, but I think the filesystem will be further downplayed as Apple tries to take its vision of user friendliness even further. This is the possibility.
2. Window management goes away. Imagine software that didn't need its UI sorted and resized. Personally I hate even thinking about where something should rest on a screen. Given that there are tons of legacy applications out there that use windows in a variety of ways I don't see this happening. This is the dream.
-- Edit:
Graphics drivers that are on par with Windows should probably be added to the "dream" category.